The short answer is everything without a height restriction.
At 6 months, DS did well on pretty much all the Fantsayland rides - he really liked IASW, Peter Pan, Pooh, etc. He slept through the darker rides - POTC, HM. The only thing to watch out for was the noise level - the movies, such as Mickey's Philharmagic, were really just too loud for him, plus, he wasn't interested in sitting thru them unless he was napping.
Epcot has rides in Mexico, Nemo, and the Land, Spaceship Earth, etc.
Also, check out the babycare in all the places - nice place to feed baby, nurse, change diapers, etc.
For strollers - at 6 months we used the umbrella stroller Disney sells - it worked just fine for us, and DS slept well with the slight recline. By 8 months we took a Maclaren Triumph - it was easier to carry on the busses, etc. We also took a hip carrier for DS, because there will be lots of times you park the stroller and carry the baby - the hip carrier worked very well for DS at this age.