Hexblade’s Curse + Booming Blade’s secondary damage

While trying to minmax a build for a Bladesinger by way of the new TCoE book I happened upon a curious problem with which I need assistance. The bonus damage from Hexblade’s Curse reads

[…] You gain a bonus to damage rolls against the cursed target. The bonus equals your proficiency bonus.

So my question can be summed up as ‘What constitutes a separate damage roll?’ Are damage rolls separated by source? Perhaps by damage type? Are they separated by when the damage is dealt?

For example…

A creature is struck by a Bladesinger/Hexblade using the special Extra Attack feature in Tasha’s Cauldron of Everything; once using a 7th level Shadow Blade, and once using Booming Blade. The creature is under the effects of Hexblade’s Curse.

How is the damage calculated? Is the Hexblade’s curse damage applied to the initial strike, the second strike, and the damage the creature takes when it moves? Or is the curse damage ignored when the creature moves since the source of that damage has already dealt the curse damage?

Does the damage roll for an attack made by the effects of booming blade count as a damage roll made for booming blade?

This question is worded very specifically so think carefully about the wording before you answer. The description for booming blade goes as follows:

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and then becomes sheathed in booming energy until the start of your next turn. If the target willingly moves 5 feet or more before then, the target takes 1d8 thunder damage, and the spell ends.

If the damage roll made by the weapon also counts as a damage roll for the spell, then the damage roll would also be under the effects of things like the elemental adept feat since elemental adept specifies that the spell has to deal that damage and not the damage roll.

When you gain this feat, choose one of the following damage types: acid, cold, fire, lightning, or thunder. Spells you cast ignore resistance to damage of the chosen type. In addition, when you roll damage for a spell you cast that deals damage of that type, you can treat any 1 on a damage die as a 2.

Does it apply to the damage roll of the weapon or only the bonus thunder damage?

Can the spell Booming Blade be affected by the Twinned Spell metamagic?

Booming blade is a Sword Coast Adventurer’s Guide cantrip that allows the spellcaster to make a melee weapon attack with their weapon and add additional power to the attack:

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and then becomes sheathed in booming energy until the start of your next turn. If the target willingly moves 5 feet or more before then, the target takes 1d8 thunder damage, and the spell ends

Booming Blade, Sword Coast Adventurer’s Guide, pg. 142

The Twinned Spell metamagic permits a Sorcerer to take any spell that targets only a single creature, and cast it twice, targeting a different creature.

When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip).

To be eligible, a spell must be incapable of targeting more than one creature at the spell’s current level. For example, magic missile and scorching ray aren’t eligible, but ray of frost and chromatic orb are.

Twinned Spell, Player’s Handbook, pg. 102

It has been commonly accepted that this is a valid use of this metamagic/cantrip combo, but a recent Errata to the spell has changed its range to "Self (5-foot radius)". Is this spell still eligible to be Twinned?

Does the material component of Booming blade need to the same one used in the attack?

Does the spell specify that the material component need be the same as the one used in the attack?

As part of recent errata to the green-flame blade and booming blade cantrips, their material components have been amended to "a melee weapon worth at least 1 sp" (Sword Coast Adventurer’s Guide, 142).

If not then can you use a separate sword for the component?

Can the blade created by Shadow Blade be used with the Booming Blade or Green Flame Blade cantrips?

The spell shadow blade allows a spellcaster to produce a discrete weapon that can then be used to make attacks:

You weave together threads of shadow to create a sword of solidified gloom in your hand. This magic sword lasts until the spell ends. It counts as a simple melee weapon with which you are proficient. It deals 2d8 psychic damage on a hit and has the finesse, light, and thrown properties (range 20/60). In addition, when you use the sword to attack a target that is in dim light or darkness, you make the attack roll with advantage.

Shadow Blade, Xanathar’s Guide to Everything, pg. 164

As part of recent errata to the green-flame blade and booming blade cantrips, their material components have been amended to "a melee weapon worth at least 1 sp" (Sword Coast Adventurer’s Guide, 142).

Can shadow blade still produce a weapon that can be used with these cantrips?

What are the repercussions of the Sword Coast Adventurers Guide errata to the cantrips Green-Flame Blade and Booming Blade?

In the most recent update to the Sage Advice article, Green-Flame Blade and Booming Blade have received errata to their range and spell text, being altered from

Range: 5 feet

to

Range: Self (5 foot radius)

Furthermore, the text of GFB and BB have been altered from

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell’s range, otherwise the spell fails.

to the phrase

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you.

How do these changes alter the way that these spells are used, and how they interact with features or feats, such as Spell Snipers effect of doubling a spells range.

if booming blade or green flame blade are counter-spelled, does the attack still go through?

Booming blade says:

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell’s range.

Counterspell reads

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 3rd level or lower, its spell fails and has no effect.

Does counterspell interrupt the attack made in conjunction with casting booming blade?

Can you Greenflame Blade / Booming Blade with a Shield? [duplicate]

Both these cantrips want a weapon as the material Component, and then later want a weapon attack. However if you are an Arcana Cleric (learns a wizard cantrip), and as a cleric you can use your shield as the spellcasting focus (ignoring the 1st requirement).

But can the shield be considered an improvised weapon for the 2nd requirement?

What is the interaction between Empowered Spell and Booming Blade or Green-Flame Blade?

Can you reroll the damage dice that come as part of the melee weapon attack? That is, is the melee weapon attack part of the damage for the spell?

Empowered Spell reads:

When you roll damage for a spell, you can spend 1 sorcery point to reroll a number of the damage dice up to your Charisma modifier (minimum of one). You must use the new rolls.

Booming Blade and Green-Flame Blade read:

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell’s range, otherwise the spell fails.