Sorry in advance for the lengthy question and tell me if I posted to the wrong forum.

We have an 1800 sq. ft.(900 downstairs & 900 upstairs), 2 bath, house in North Central Washington State. The house was built in the late 60's. Before we got the house, it sat empty for a number of years and had not been weatherized before it was shut down. During the remodel we had all of the plumbing redone because most of the pipes had burst and we added a bathroom upstairs. The water service is from an on-site private well. The pressure tank (small), pressure switch and pump controller are located in a 4' diameter concrete manhole, with a concrete lid, which is heated by a 2' baseboard heater. The well is about 60' deep with a pitless adapter and a 1 hp submersible. The well is 15' to 20' below the house. All of this is about 80' from the house. I would like to abandon the manhole and install a new line from the well to a new (yet to be built) 8' x 12' insulated shed adjacent to, and 10' from, the house. Then run a new line into the house and tie into the existing 1" copper in the house. Right now the plumbing in the manhole appears to be 3/4" galvinized but the line coming into the house is 1-1/4" thin walled PVC. I don't have a clue where the transition from galvinized to PVC was made. If I run an all new line from the well, am I limited in what material I can use and what size would you recommend? Also, I was wondering what sized pressure tank I should use. The tank in the manhole measure 20" dia. and is about 36" tall, including the base. The existing system cycles frequently and I'm a little concerned about the effect on the pump. My main goal is to get all of the stuff now in the manhole into a space which can be heated without spinning the meter off the pole to keep everything from freezing. Again, sorry if it's too much info.