Can one class’ feature help another class qualify for a feature?

It’s best to just give an example for this:

Let’s say I have levels in a rogue archetype that gives up Evasion, but I take a two level dip into monk to get Evasion. Would I qualify for the Improved Evasion advanced talent upon reaching rogue level 10? (yes, I know RAW Improved Evasion has no Evasion prerequisite but I doubt most GMs would let you get away with taking it without Evasion)

Or if I had levels in an alchemist archetype that gave up Mutagen, but took a dip in Mutagenic Mauler or Mutation Warrior, could I take alchemist discoveries that affect mutagens, as an alchemist, and apply them to the dip class’ Mutagen?

If I’m proficient with a bastard sword, does that qualify as being proficient with a martial weapon?

My character is a Kensai, which means he is only proficient with simple weapons, and one martial or exotic weapon of his choice. He has chosen proficiency with the bastard sword.

A bastard sword is about 4 feet in length, making it too large to use in one hand without special training; thus, it is an exotic weapon. A character can use a bastard sword two-handed as a martial weapon.

Upon reaching 8th level, he would like to enter the Student of War prestige class, but that prestige class requires the character to be proficient with two martial weapons.

I can get longsword proficiency with the Arodenite Sword Training combat trait (technically I can get klar and earth breaker proficiencies with the Shoanti Tattoo trait but for the sake of the question let’s say I’m not a Shoanti), but would I have to take a Martial Weapon Proficiency feat to qualify for Student of War?

Can the Telepathy spell convey enough information to qualify a location for Clairvoyance or Scrying?

Clairvoyance and Scrying are both useful spell for seeing a specific location:

You create an invisible sensor within range in a location familiar to you (a place you have visited or seen before) or in an obvious location that is unfamiliar to you (such as behind a door, around a corner, or in a grove of trees).

or

you can choose a location you have seen before as the target of [scrying]. When you do, the sensor appears at that location and doesn’t move.

If I want to create this sensor at a location I haven’t seen before in person, can I gain enough knowledge through telepathy to do so? Keep in mind that telepathy can share images:

Until the spell ends, you and the target can instantaneously share words, images, sounds, and other sensory messages with one another through the link…

…so I’m mostly wondering if images of a location are enough to qualify for clairvoyance and scrying‘s "seen before" requirement.

Can you benefit from the Dueling fighting style for one weapon, then draw a second weapon as part of Extra Attack to qualify for Two-Weapon Fighting?

Say a Champion fighter has the "Two-Weapon Fighting" fighting style and the "Dual Wielder" feat. At 10th level, they pick up "Dueling" (+2 to damage rolls when wielding a single one-handed melee weapon) for their 2nd fighting style. Since they’re 10th-level, their Extra Attack feature lets them make 2 attacks as part of the Attack action.

Can they have one weapon drawn for their first attack, to benefit from Dueling – and only then draw another weapon for their second attack in the Attack action, in order to meet the requirement for Two-Weapon Fighting (and thus deliver another attack with their bonus action)?

Is it possible to qualify for a Greater Dragonmark in E6?

I’m considering running an E6 game in Eberron, and I’m curious if there is some way to qualify for the Greater Dragonmark feat.

Skill Beyond Your Years and Primary Contact can let me reach 12 ranks in a single skill, but the feat requires 12 ranks in two different skills. I’ll likely houserule it, should there not be a way to reach it, but I’m curious if anyone knows of another way to reach 12 ranks in a skill in E6 (or some other way to acquire the Greater Dragonmark feat).

Do Dvati qualify for Multiweapon Fighting?

They have 4 arms between them. A Dvati ‘character’ taking the feat has 4 arms. OTOH, of course, if you look at them as separate creatures, neither qualifies. …I’m leaning towards the first interpretation, honestly, but what are your thoughts?

“Would this actually benefit them, anyway?” I hear you asking. Actually, yes. If the ‘main hand’ attack is, for instance, an unarmed strike with the leg, both hands a free for extra attacks courtesy of Multiweapon Fighting.

When substituting one ability for another on a skill check which kind of check does it qualify as?

The Unearthed Arcana Monk tradition Way of the Astral Self has the following ability (page 2 of the PDF):

Arms of the Astral Self

You can use your Wisdom modifier in place of your Strength modifier when making Strength checks and Strength saving throws.

Imagine such a monk took 1 level dip into Barbarian and picked up that class’s rage ability which includes:

You have advantage on all Strength checks and Strength saving throws.

If the monk goes to make a strength check (say, a grapple check), does the monk have advantage on the check because it counts as a strength check (but she’s using her wisdom modifier)?

Or does she roll a normal check with her wisdom modifier because it’s now a wisdom check, as determined by the fact that she’s using wisdom for the check, not strength?