Giant Insect and Ranger’s Companion

In the Players Handbook I noticed Giant Insect spell. Everything is clear with text, although the non-standardized wording is a little embarrassing. However, I was interested in the presence of Spider and Scorpion in arthropods list (I will further mention only the Scorpion), since they can be Beastmaster’s pets. It looks like interesting function, but in this case intersect two very unique override texts (Giant Insect spell and Ranger’s Companion skill), from which many questions arise.

Giant Insect

[…]

You transform up to ten centipedes, three spiders, five wasps, or one scorpion within range into giant versions of their natural forms for the duration. A centipede becomes a giant centipede, a spider becomes a giant spider, a wasp becomes a giant wasp, and a scorpion becomes a giant scorpion. Each creature obeys your verbal commands, and in combat, they act on your turn each round. The GM has the statistics for these creatures and resolves their actions and movement. A creature remains in its giant size for the duration, until it drops to 0 hit points, or until you use an action to dismiss the effect on it. The GM might allow you to choose different targets. For example, if you transform a bee, its giant version might have the same statistics as a giant wasp.

Ranger’s Companion

At 3rd level, you gain a beast companion that accompanies you on your adventures and is trained to fight alongside you. Choose a beast that is no larger than Medium and that has a challenge rating of 1/4 or lower (appendix D presents statistics for the hawk, mastiff, and panther as examples). Add your proficiency bonus to the beast’s AC, attack rolls, and damage rolls, as well as to any saving throws and skills it is proficient in. Its hit point maximum equals its normal maximum or four times your ranger level, whichever is higher. Like any creature, the beast can spend Hit Dice during a short rest.
The beast obeys your commands as best as it can. It takes its turn on your initiative. On your turn, you can verbally command the beast where to move (no action required by you). You can use your action to verbally command it to take the Attack, Dash, Disengage, or Help action. If you don’t issue a command, the beast takes the Dodge action. Once you have the Extra Attack feature, you can make one weapon attack yourself when you command the beast to take the Attack action. While traveling through your favored terrain with only the beast, you can move stealthily at a normal pace. […]

  1. Im correct that the transorm form isn’t "true form" of creature, and the Giant Scorpion still remains Ranger’s Companion with all the bonuses? In fact, the Scorpion only has replaced Statistics and all other buffs/effects remain?
  2. In Giant Insect lacks typical text, unlike other similar "transform" spells:
    The target assumes the Hit Points of its new form. When it reverts to its normal form, the creature returns to the number of Hit Points it had before it transformed. If it reverts as a result of Dropping to 0 Hit Points, any excess damage carries over to its normal form.
    In this case, do I understand correctly that for this transformation all these points are invalid? I’m only confused by the beginning, because then the Giant Scorpion gets Hit Poins of common Scorpion, or this part of the text implied in "The GM has the statistics for these creatures…"?
  3. Ranger’s Companion text and the Giant Insect text contain a unique override rules of acting. These rules are override or mashup with each other? In case of override, then Giant Insect begins to follow the rules of the Ranger’s Companion, or vice verse?
    Correct my interpretation if I’m wrong. Rules do not contradict each other, and hence mash up. The companion gains the same initiative as the player (Ranger’s Companion), but acts on the player’s turn (Giant Insect). Both the spell and the companion rules allow me to control the Giant Scorpion, but in case of spell the commands could be interpreted by GM, and now GM’s jurisdiction is limited to the need to accurately execute my commands. However, now the Giant Scorpion can not perform any actions except Dodge if I don’t order command with my action.
  4. The question is purely formal. Logic suggests that the word act is explained here:
    ...and resolves their actions and movement
    But the term itself is very confusing. I do understand correctly that the word "act" in context means "actions", "bonus actions" and "move" together? Or this term completely free for DM interpretations?
  5. Additional question. If we agree that act is all activity and that interpretation in the third paragraph is correct, what happens if we mounted Giant Scorpion as independent mount? I understand correctly that the Giant Scorpion turn separately from us, gets its turn with our Initiative, but will act on our turn? Im correct that in this way we get a "controlled" mount in fact (Actually independent, but which moves on our turn according to our commands), which will not be limited in actions among other things (Only by the rules of the companion, and if they are not there, then any actions are available)?