Vitamins - Ideally they shouldn't contain sugar, yeast, gluten, etc...Because there is usually no need for that junk. Should you be overly concerned about this stuff? I'd say no, unless you're taking mega doses of a particular vitamin, in which case filler and extra junk starts to add up.
Probiotics - Fine to take whenever, its just that if you take some while eating a raw clove of garlic, a lot of the probiotics may end up being wiped out before actually doing any good. Timing is important to maximize the effect. ie. Taking an anti-fungal before bed, and taking a probiotic first thing in the morning. Basically kill the yeast/whatever, then fill in the gaps with beneficial probiotics.