Will certain foods I eat while I'm breastfeeding cause my baby to get gas?

Yes. Some foods in a mother's diet seem to be linked with increased fussiness or gas in their babies. Some culprits seem to be dairy, brussel sprouts, legumes and ither cruciferous veggies. The only way to see if this makes a difference in your baby is to try cutting one or more of these foods out of your diet and observing anh changes in your baby.
None. Gas in a breastfed baby is swallowed air, has nothing to do with your diet.