You can do the gramma and a wrasse at the same time if you want.
If you plan on keeping more then one wrasse in the tank you should try and add them together if possible, but wrasses in the Halichoeres Genus are generally more peaceful. Just be careful and don’t accidentally get yourself a Six Line Wrasse. They’re eye catching but some become real ******s.
Tomini Tangs are a type of Bristletooth. The ones that stay on the smaller side are the Tomini Tang, Kole Tang, Two Spot Tang, White Tail Tang and the Square Tail Tang. Prices on them vary quiet a bit.