Yes they have gift certificates. Just ask your server and they will be happy to oblige.

They have just about everything that a typical northern Italian restaurant would have as well as rotating specialties. All of the dishes are made to order, the implication of that is that it takes a significant amount of time to get your food once you have placed your order. Do not go to Giovanni's with the expectation that you will order and eat within an hour. That said the food is very good and at least in my experience worth the time.

Via the delivery apps, yes

No but they have meat and vegetarian strombolis which is like a calzone but better

I always call them when in doubt.