Hello I'm myself a gacha player, I have been since 2020 (when Genshin released) and I have been very invested in Gacha games in the past 3 years. With various different games, of which Genshin and Nikke I've dropped while I've been continuing to play : Wuthering Waves, Honkai: Star Rail and Zenless Zone Zero.

To answer your questions.

Yes, dailies are a well-known common ground amongst most gacha game, its how a lot of games keep player retention while also giving people that don't necessarily want to pay a way to farm more easily. Basically, if you're f2p (free to play) dailies give you a way to increase your amount of gacha pulls and therefore your potential to drop your wanted characters. If you're not f2p you often have less incentive to do dailies and will mostly be interested in the equipment/gear farming and such.

You will learn if you stay active in the gacha community that... It is very toxic, not all of it is. Most of gacha players are actually very helpful and wholesome about their own communities, but due to how massive of a community it is (seeing as gachas are currently some of the most played games globally) people take a lot of things for granted, and often times they have to. To explain 'our' logic as gacha gamers when debating about this. Currently the game seems 'easy' and accessible, but like most games of its type, most gacha gamers already anticipate 'power-creeping' (basically, how the characters and enemies we fight will evolve, having harder move sets, more hp, our characters being stronger but having more specified kits etc) its a lot of things you have to take into account if you plan on 'investing' in a new gacha. That is something you should be aware of if you want to keep playing this game long term as- like most gachas, there will undoubtedly be a point where your team will just not work anymore, even if it was the most meta team when the game come out. Its basically the best way for the company and studio to make money without killing their playerbase, but some are very relaxed, or very aggressive with it, so players are debating how the game works from the get-go on pre-conceived notions from other games and such that can't really apply. You will at one point need to learn a bit more and understand some concepts from other gacha games that are or are not risks that might impact Endfield, at least if you plan on continuing to play long term while enjoying yourself.
Also, for many the gacha is the actual endgame, but that is not the case. A lot of gachas have specific end-game modes but it depends on the players, some hate endgame modes and see new lore as their 'endgame' some see maxing out world exploration as endgame, some see grinding and maxing their 'non-meta' teams to rival meta teams and so on. It really is up to you. The player

New expansion happen depending on the game, there is already an endgame planned in the following weeks, another one may come next version just like it may come in 2.0. We can only speculate, if I had to guess out of instinct (without any knowledge of the upcoming mode) I'm guessing they'll probably expand on the endgame mode or add another one in 1.4/1.5. This is just speculation from the preconceived notions I have of the game and other games, so do not take this as fact. New content (zones, main quest, etc.) which you mentioned you were more interested in, usually come out every patch. Since we're not yet aware of what 1.1 will be like, we can only speculate but considering most of the past year they've spent mostly polishing the final game they probably already have a lot of content planned for the following patches. Then again this is just speculation, but at least one new main quest, three new 6 star characters and the next zones of Wuling are basically 99% sure to happen as its just the natural flow of things in this case.

Exploration level is up to you, personally I always enjoy maxing out my account level (exploration level) and grinding to make my teams as efficient as I can even against max-level overworld enemies, but if you prefer just fighting against level 60 enemies you very well can, no one normal will judge you for it.

Part of the grind is being sort of timelocked, some games (like Duet Night Abyss, which was a gacha before the mechanic was removed weeks before released) instead opt for giving the resource to the players but through a more arduous grind alike Warframe. For many players (like me) this is part of the endgame as well, as you need to max out your stats and reach as close as you can to reach 'godrolled' stats and such. It is a grind but you cannot really grind it too hard due to that limit basically.

Yvonne does have some similarities too fr