Hi hammeroflove99, welcome to the forum!
In answer to your questions:
Yes, you can mix them. The consumer products here can be used alone or in combinations. Make sure you test each one out individually first, so that you are familiar and comfortable with the effects and dosages of each, which can vary from person to person. This post might help How To Find Your Sweet Spot (How to find your sweet spot...)
TUTH is best used in an already sexually charged situation, such as alone with someone who is ready to take things further. Worn in a non-sexual environment, such as work, school, church, at the store, etc., you risk giving off the aura of a horny toad who only thinks about sex. Other more experienced users have used it in combinations during such times and gotten away with it, but its tricky, so be careful.
Instant Openness is perfect for approach anxiety, which is very common. IO will relax you and those nearby, making all involved friendlier and more talkative.
I can’t say about IFM as I’ve never tried it, but I understand that A1 is quite similar.