Like everyone else said the concern comes from whatever is leeched out of the plastic bottles during heating.
We formula fed our son from 8 weeks onward and never heated bottles. We kept water at room temperature for mixing his bottles. With the formula premeasured, it made bottle making (especially in the wee hours of the morning with a half asleep parent and a hungry customer) a snap. It did also make travel so much simpler since our son didn't need heated bottles. Combine water and formula, feed kid = happy family regardless of settings.
My go to gift for first time parents are the non-glamorous things - nail clippers, hair brush/comb, medicine dispensers, basic medicines (teething gel, gripe water, etc.), a thermometer, cloth diapers (good for burp clothes, spills/messes, etc.) and other assorted practical items. Whatever fits my budget determines how much goes in the gift bag. I am sure whatever gift you decide on will be appreciated, though, so I wouldn't worry too much. Good luck.