Yeah it sounds like fuel pump diaphragms to me, if you prime it back up and you can feel the fuel go in then i think you should get a diaphragm kit for it.
As for the power trim its quite easy to take of but really you need some kind of lifting gear to support the engine, because once you remove the pump the only thing holding the engine to the leg is the steering tube. You will also have to loosen the steering tube to move each transom bracket out to give you enough room to get the pump out. Actually now i think about it probably better to get your local dealer to do it!!!.
You can get seal kits for them and brushes etc which can be difficult to change if you dont have the right service tools. Probably another dealer job!!.
I guess your engine is out of warranty?