FTM and formula fed baby

Hi I’m a ftm and decided to formula feed my baby. I was way too emotional / stressed and defeated to breastfeed and my baby is only 3 days old. I have some questions if anyone can answer them tho! So how much should I make for him? Also is the similar pro advance good for him? I haven’t noticed too much gassy ness or anything abnormal and today is the 2nd full day. Also should I refrigerate it or how should I store it? Thank you to anyone that helps!