Firstly, congratulations! Secondly, it is not unusual for a baby to get hiccups, it could be that he is swallowing too much air with his feed or taking it too fast. The best, and to my mind the most sensible thing to do is to speak to your midwife or health visitor about your concerns. They are specialists in this area and will give you as much guidance and help as you need. Don't continue to worry and fret alone, there is help out there, you just need to ask for it. Good luck to you all!

If she wants to bf exclusively then i'd advice against giving formula.
Breast milk is produced by supply and demand. So if you top up with formula then she will stop producing milk.

As for the hiccups it could just be a little bit of nipple confusion (between breast/bottle) and is gulping too fast on the bottle because milk is harder to extract from the breast if that makes sense.

try smaller anounts and break up his feeding time a little more

Probably too late for this but if you dcided to BF exclusively then DO NOT give formula! Pump breast milk and feed with bottle otherwise baby will prefer formula. It can takes a few weeks for baby and mom to get the hang of things. And can be extremely frustrating but keep with it. If she is giving Formula and not pumping her milk supply will go down. Hiccups are normal.

read the book what to expect the early years...or something like that. pick it up at the book store...its a wealth of info