Hi all,
Long time reader but with no practical knowledge. We are  in the midst of an update to the heating system of our 25 year old 2432 sq. ft home in southern Maine. I have done a heating load calculation using our past year midwinter oil usage and came up with a total load of 36,561 @ base 65* heating degree days. We have a unfinished basement that is roughly 1200 sq. ft that has insulation on the walls above ground level with a heat pump hot water heater located in one corner. Our first floor is about half open concept style, typical of colonial style house construction of the 1990s in New England. The upstairs has 3 bedrooms; one a master suite and two small children’s bedrooms (each small bed is about 125 sq. ft.). I believe we are slightly better insulated than standard build in the area because the owners who built the house worked for an insulation company and the attic has quite a bit of blown in cellulose insulation but this is just a guess based on the attic insulation.

I am hoping for a little guidance on the design of the system, though I realize without accurate load numbers for each bedroom you are all flying a little blind.  I have received multiple quotes, all of which recommend putting 6 heads in the house (one in the basement, two on the first floor and 3 on the second floor in each bedroom). After reading many articles on this site this seems oversized, even if our house is not super tight.  

My main questions are;
1. Am I correct in thinking that putting multi zone 7k heads in the two children bedrooms is a bad idea? All the contractors have defended this when I have asked them about it.
2. All contractors recommended putting a head in the basement (one put a Daikin 7k the others had larger 12 or 15k units). I think putting something in the basement seems like a good idea but am not sure and also am not sure how to think about sizing that unit. 
3. All contractors are recommending two multi-zone condensers, either two 24k units or two 30k units, (for example one wants to have the basement unit and two bedrooms served by one condenser and the other condenser serving the two main floor heads plus one bedroom). Would it be a better idea to have a condenser essentially for each floor (with the idea that there would be no heads in the kids rooms, so only one upstairs)? My thinking is each floor has different heating needs than the others. 
4. Given my heat load calculation and the fact that I don’t believe any of the contractors did a manual J, can I assume a 48k system will serve the whole house well? Or is that too oversized? We do have a wood stove on the main floor but want the system to be sufficient in all but the coldest polar vortex type scenarios.

Thank you all for the help!