Just dove into my first tiling project in a remodeled bath. I laid about 50 sq' of porceline 12" tile. The tiles are laid and have been drying for about 20 hours now. I've impressed myself

I'm heading out soon to pick out some grout and sealer. I used Mapei thinset on top of hardi backer and plan to get mapei grout. I've been watching numerous do-it-yourself videos online on how to properly grout tile. I don't expect to have any problems. But I do have a few questions concerning grouting and sealing.
The tiles are porceline and located in a bathroom. After grouting the tiles how long do I need to wait before putting sealer on the tiles? Considering I put porceline down instead of natural stone I assume I need to just put grout sealer on the joints themselves rather than over the entire tile. Is this true? Also, how many coats of sealer should I put on? How long will the sealer need to dry before I can reinstall the toilet and vanity?
Lastly, what color of grout do you recommend for the tile I installed. The tile store had them on disply with grey grout and it looked nice. I wouldn't have ever picked grey if I had't seeen it on display. My first guess would've been some type of beige color. What do you think?
Heres a pic.