I'd say have a look in the boat trader,ebay, local classifieds.As for what you need life jackets,flares,radio(not for music ),back up engine or oars,gps.as for were to keep it that depends on where you live and how often your going to use it,it all boils down to cost.you could moore it up(cost effective if your using every week) or launch it every time.look else where on the internet for more info on what to look for when buying a boat.No there is no catch quoter for sea fishing with a rod and line.
hope this helps a bit.
Chopper28