Thanks for the advice guys, really helpful.
I have been throwing everything at my protag lol. If I remove him from the party who is best to bring in?
I have Jean, Amber, Kaeya and Protag
Kick protag and work on
Lisa
Noelle
Gorou
Xingqui
Barbara?
Havent got enough mats to boost them all.
Thanks for all the help
Xingqui is the only long term investment safe character you have, if you don't mind his design. I hate him and everything he stands for.
Otherwise, your party of 4 is fine for getting through the story. When you get one of the better DPS characters, you will drop the protag and Kaeya likely for good. Amber like I mentioned before is a necessity in your overworld party for puzzles. If you swap her out, you'll constantly have to put her back in the team to progress, so just plan on her being a mainstay. You eventually get Xiangling for free from the endgame-tier content (The Abyss), she will be a better DPS and support than any of your other characters once built properly. She's a Pyro spear character. You only need to beat level 3 or 4 or something to get her, so you should be able to do it when your characters are around level 60, but don't quote me on that.
Otherwise, you will eventually get better damage characters, and they're more "flavor of the month" than the supports. I can't stress enough how much of an improvement Zhongli and Ganyu will be though. Then you could pretty much coast through the game with Ganyu/Zhongli/Xiangling/Jean and nothing could stop you.
Thanks again for all the help guys.
How many characters can you actually take to max level?
Ive been being careful so as not to fuck my prospecta of levelling a really good one later on down the road, and I assume the xp dries up once you have opened all the chests etc
All resources are farmable. You cannot waste resources. As you get stronger and your world level increases, the level and difficulty of the enemies increase, but also the rewards. By the time you're level 80, you get like 8-10 purple books and ~14 blue xp books per run of a farmable event. This is the purpose of the "resin" system. I think you probably have it unlocked, but it's a little icon you can see in your world map that maxes out at 160. You use that stuff as "stamina" to farm for pretty much all growth materials. Mora (this game's money currency), XP books, Talent/weapon/ascension materials are all tied in to that one regenerating resource - resin.
Once you have it unlocked, you should be trying to keep burning it as not to waste any. At this point in the game, you need every material, so don't worry about what you're using it on, just use it. After you start running out of one thing or need certain materials, then you can plan out what you're using it on a little better. There are daily rotations for a few of the materials that can only be farmed on certain real life days of the week.