Splendor: Marvel

You must have the required bonuses shown on the Location tile (tokens are not taken into account); if you have them at the end of your turn you must take that Location and gain its 3 Infinity Points, and taking a Location is not an action (page 4).

No — you cannot take Gray or Green tokens with those actions; Gray tokens are only gained when you reserve a card (if any are available), and Green tokens are gained when you recruit your first level‑3 character that shows the Time Stone icon (page 3; Time Stone rules page 4).

The end‑of‑turn 10‑token limit counts all colors including Gray and Green, and you must return tokens of your choice to reach 10 if over, but Green tokens must be kept and cannot be returned; also no player may have more than one Green token (pages 3–4).

Yes — you may still reserve a faceup card or draw blind even if there are no Gray tokens, but you simply won't receive a Gray token; players can have at most 3 reserved cards and reserved cards remain in hand until recruited (page 3).

Yes — any Character card taken from the middle (recruited or reserved) must be immediately replaced by a card of the same level so there should always be four faceup cards of each level unless that deck is depleted (page 3).

When a player meets the Gauntlet conditions the current round is finished so every player has the same number of turns (if the triggering player was last in the round they win immediately); if multiple players meet the conditions the tie is broken by most Infinity Points, then ownership of the Avengers Assemble tile, then fewest Character cards, otherwise the tied players share victory, and if the triggering player later loses the Avenger tile and falls below 16 points the game continues (page 4).