The pump is already there but hasn't been used in 25 years. There is a really old Submercible pump control box in the well house(should I replace it?). Previously there were three wires run to the pump. 2 hots and a neutral I think. I still have the old breaker box so I can see how it was wired.

I don't have a bladder tank what is a good size to buy for a single person(eventually I want to add washer and dryer)? Do I just rewire it then add a bladder tank or is there other things that I need to add? The old system was for a trailer house. The new system will be for a park trailer.

The pump is already there but hasn't been used in 25 years. There is a really old Submercible pump control box in the well house(should I replace it?). Previously there were three wires run to the pump. 2 hots and a neutral I think. I still have the old breaker box so I can see how it was wired.

I don't have a bladder tank what is a good size to buy for a single person(eventually I want to add washer and dryer)? Do I just rewire it then add a bladder tank or is there other things that I need to add? The old system was for a trailer house. The new system will be for a park trailer.

You're asking about a existing submersible pump and how it hooks up, Correct. A small bladder tank should handle your needs. These may help. Good luck, Tom

I just asking about water pressure bladder the size meaning the gallons that I might need to purchase a new pressure tank

It depends to some extent on how much usage you will have, but something in the 35 to 50 gallon range is typical, something like this:

Shop Water Worker 44-Gallon Vertical Pressure Tank at Lowes.com (http://www.lowes.com/pd_424500-41278-HT44B_0__?productId=4095301&Ntt=water+pressure+tank&pl=1&currentURL=%3FNtt%3Dwater%2Bpressure%2Btank&facetInfo=)