DPS can go up to lvl 80 while most supports stays at lvl 60 only. Don't bother going to lvl 90 even with your DPS, cause the amount of exp books needed to bring a lvl 80 to lvl 90 is the same as bringing a lvl 1 to lvl 70.

You'll need 2 teams for Spiral Abyss anyway. So you'll need 8 playable characters at least. Most people tend to focus on the first team until AR45 anyway. So don't stress about the 2nd team so soon.

Like I said, don't stress about it lol
You don't have to build another 4 characters immediately. I did it in phases. For floor 5 to 7, I actually pulled it through with just 6 playable characters; 3 in each team & a filler as the 4th character. By floor 8 onwards only have 2 full teams.

It just takes time.

After u finish the story quest etc, it's all bout farming for gears and upgrade materials.

Three 5 stars in 30 pulls?
That’s really lucky.

Just put in resources into your main dps.
Diluc is an excellent main dps and keqing isn’t bad either.
You can have one lead team A and the other team B.

Xingqiu would be the best support for diluc. His ult will always apply hydro for every attack of diluc's so close to 100% vape. Mona.... she's great if you can build the party around her la, otherwise probably razor-kaeya combo is better.

I wanted Wolfgravestone...but instead got staff of homa. Now i need to figure out the build and set ups to fit my zhongli with the staff...really wanted wolfgrave for diluc....