The most important thing with basmati in my experience:
1) Use two to one measures by volume (2 parts water, 1 part rice)
2) Gently bring to a simmer (5 min) then ruduce to a very low flame and heat (covered) for about 15 min
3) DO NOT STIR IT AT ALL (unless you want glue)
I wouldn't advise reheating rice cooked tonight up until Friday. get the extra in the fridge asap and it should be OK for a couple of days but make sure you heat it properly.