1 -) what type of Arduino is right for me? I've been researching the Mega 2560, Arduino UNO REV3 and MINI models.
ps: I need to put the arduino with these components on a boat, takes up less space as possible inside the boat, then if the arduino MIni work, it will be even better.2 -) which and how many entries I'll use in Arduino (how many analog inputs and PWM inputs are necessary for each component)
All of this is on your end, you need to do the research. Go through each component and see what each one needs to work. Count up the number of pins each one uses and then see what board is right for your needs. You need it to be small so your options are the Nano, Micro and Minis or you can make your own arduino from scratch with Bare Bones Arduinos.
Added: since its going to go into a boat, your going to want water proof casing or some way to prevent water from entering. Look into water proof servos too.