Please help!

So, I have been avidly reading The Owner-Builder Book and I have a few questions that I am hoping my fellow O-Bs can answer... Our beautiful dream home is going in for plans to the designer this Saturday at 2,400 sq. feet for the main level and another 1,100 for a nice big den/kid's playroom downstairs.

1. I am wondering what kind of heating would be most beneficial to us without breaking the bank, as one would say? I have heard pros/cons of geothermal vs. forced air for months now and we still can't decide. We will be putting in a wood burner downstairs in place of a fireplace (gas upstairs). Any input on this topic would help greatly.

2. Our fixtures, appliances, and basically anything else that is bought at a Lowe's/Menards/Fleet or other home center store - my question is when do price them out? I've been doing my homework and spending roughly 6 hours a day for the past two months on house and house-related topics. I'm putting in my 1,000+ hours of planning, but for our construction loan, they want to know detailed reports. Should I just find the top three of each category that I like and average them out? Do I choose the most expensive and allot for that? Prices vary and I'm at such a standstill about it.

3. Lastly, can a perc test be done in a construction loan? We have put ourselves into a tight position for the next month n a half, because we paid for our land (four acres/wooded) up front without a loan. My husband and I are concerned and really want to know if we are going to have to push back our groundbreaking date of July. What all can be put into a construction loan?

I'm sure there are other questions that I'll come up with, but it really does help to know that I have this amazing resource here for when I get frustrated or confused. 

Thanks in advance!

Shannon