Most R/C transmitters use a 9.6 volt pack of AA sized rechargables.
Years ago these would have been nicads, these days they will be NimH. They are avilable in various capacities, but I would recommend looking at Sanyo Eneloop NimH. These are very low self discharge, and unlike conventional NiMH technology which lose charge very quickly, Eneloop batteries retain 80% of their charge after a year sitting on the shelf, and the latest versions 90%. These are just like using dry cell batteries.
So purchase eight of those, and wire them into a pack. Amazon and ebay are good places to look, and there are one or two other companies producing low self discharge NiMH batteries.
Regarding the receiver pack, most of us use the BEC (battery eliminiator circuit) which is built-in to the vast majority of ESC's these days. Unless you're running a lot of servos, they're usually perfectly adequate. If you're running three or more servos, you might want to think about a standalone BEC or running with a separate receiver battery. I wouldn't recommend using lipos for R/C equipment, for one unless you use a monitor of some description you run the risk of running them down too low, and secondly they chuck out a voltage too high for a lot of R/C kit, so you will need to run a voltage regulator. If you do that, you might as well fit a BEC.
Stuffing boxes are available from various places. Mikes Subworks, Norbert Bruggen, Engel, Marks Model bits.
Regarding speed controllers, that depends somewhat on the kind/size of boat you wish to put them in. For brushed control I use Microgyros and CTI Thor controllers and for brushless I've used Castle Creations and units from Hobbyking. They all have built-in BEC's.