opinions and suggestions please

Rich Davis

I live in a 170 year 2100 SF house located in the mtns of Va. that started out as being a 800 SF 2 story log cabin. The house has been added on to many times and the log part is inside of all the additions. I'm wanting to central heating and would like hydronic, the reason being that I can drill a couple 2" holes thru a log much easier than trying to put a hole for a piece of duct. Also I was given nearly 100' of 3/4"baseboard radiators. There is a hand dug celler under some of the rooms and a slab and a room with no access underneath. At this time we heat with a wood cookstove in the kitchen and a wood stove in the living room. There are a couple of rooms that have elect BB and we also have a couple portable kerosene heaters.
I haven't decided weather to go with oil or propane at this time. I'm considering a single pipe with deverter T to each radiator with TRV and constant water flow. The two rooms on the 2nd floor are not hardly ever used and at this time are not insulated. That would be my longest riser with 2 raditors. So I guess my questions are:
1 What size pipe should use from the boiler to the risers, the radiators.
2 If I don't run pipe tp the 2nd floor right away can I just stub off above the T's, I realize that when I size the system it will be oversized until I ad the 2nd floor added. I used the Slant/fin program and the heat loss is 59,500 figuring the 2nd floor insulated, figured uninsulted it's nearly 90,000.
3 I was planning to put the boiler in the celler on a concrete riser and the celler has a dirt floor, it's anywhere from humid to water running thru it, so will that humid conditions affect it especially in the off season or what can I do to protect it.
Thanks loads and I'm sure I'll be back with more questions.