Question about development:

[Wizzington]

0-50% from terrain, climate can add on up to 50% more.

You probably don't want to be developing in Arctic Mountains.

Farmlands are the best because they have no extra cost and also add +2 building slots.

 

[Wizzington]

So I had another question:

With the HRE having it's development cost in 1444 reduced do all the many many many nations still lead to it being the most developed location by say the 1600s? My gut tells me since they're in a nice climate without many mountains that the ~50 nations would make the HRE a wonderland.

There is no HRE development cost reduction in 1444, you have to pass the first reform.

Also, quite a bit of the HRE is Woods and Mountains.