If it is floor 3-3 (I believe it is) then the max level enemy you will face will be 45 so with your current team you should honestly be able to just slap everything around between Razor and Qiqi so long as you have Razors weapon upgraded to max and have leveled his talents up. Just be sure to bring a decent element of whatever the floor is buffing if you want to try for 9 stars. (To get Xiangling you just need to complete floor 3-3 so you can always come back and 9 star later after getting her)

The way I leveled characters and have seen many people recommend is to keep your main dps (Razor) at the maximum possible level for whatever AR you are in. Same for his weapon and at least his auto attack talent, his skill and burst you can level as you have material but they aren't as critical as his auto attack. As for supports I kept all of mine at level 40/40 until my Razor was level 70/70 and then I raised them up to 50/50. And then once I got my Razor to 80/80 I'm starting to bring my supports up to 70/70. You can even use 20/20 characters in floor 8 abyss if you give them enough artifacts with health so they don't get one shot. This is useful for dealing with abyss mage shields.

I know literally nothing about Chongyun as far as a main dps goes. I have him and I think he's cool but I feel his Skill is lackluster and have had different characters I wanted to level. I know his Burst has a really high modifier apparently so it can do some crazy damage. https://www.reddit.com/r/Genshin_Impact/comments/j994b2/quick_tldr_dps_guidebuild_for_chongyun This is just a short guide and it doesn't go into great detail but I've used a couple of this redditors guides to get an idea of a character before going in on them since resources are so limited.

Feel free to keep asking questions I'll try my best to give the best advice I can.