Unfortunetly, policies (and I believe law) require that all strollers must be folded prior to boarding the bus. If your particular stroller takes a minute or two to fold down, I might recommend taking care of it when you get to the bus stop, so that you are all ready to board when it arrives. If the stroller is too large when folded to fit through the front door, you may request to board through the back door. However, it should be noted that the stroller must be folded prior to this, and only the person with the stroller may board through the back. (The low-floor buses have a front door that is much larger than the back, so this tip is only useful for the standard floor RTS bus)
As for drinks... it's up to the driver. If the beverage is in one of the refillable mugs, and has a lid, I doubt you'd have any problems at all.
Drinks without lids, and food that might cause spillage issues (ie: cereal, popcorn, etc) might also cause problems, and you might be asked not to bring those items on board.
