As long as it's sanitizer with a shelf life like StarSan. Mr. Beer sanitizer should not be stored for more than one week in a bottle.
I wouldn't worry about a freshly washed measuring spoon, and you do not sanitize the vanilla.
Ya I think all the new brewers are on FB. Mrb is recommending fermenting in the low 70’s which goes against what I learned about mrb kits early on. I guess proof is in the results. Brewers seem to be happy with their beer.