Which Nikon DSLR ?

There is only about $100 difference between the lowest price and the highest price.
The image quality will be the same for all.
It really does not make any difference which you choose.

I would not be looking for a new lens right now.
You need to try all of your dad's old film lenses first and see which ones you want to use.

Here is some help from Nikon as to which will work with the NIKON camera you choose:

http://support.nikonusa.com/app/answers/detail/a_id/16436/kw/D5000/r_id/116678

If some of the sports you want to photograph are indoor you should choose a bright lens.
The brightest zoom lens will be an aperture of f/2.8 and they will cost more that say a lens with an aperture of f/4.0 or f/5.6