Hello!
Tamas gives some very good advice above.
When you design the printer, if you have access to a good cad-package, do some FEM-analyses on how the frame will perform under loads. You might already have thought of it, but it was some of the best advice given to me when I built my machine so i thought that someone else could use it too. And when doing this, see if you can get an analysis of how the frame flexes when the printhead moves at speeds, since this will make quite a substantial difference from when everything is still.
For XY motion I would highly suggest that you take a look into Core-XY, since this gives you a static arrangement of steppers. In theory it should also give you twice the force when moving straight in X or Y, since you have two motors working together.
For electronics, 32 bit is a must if you want to have a LCD. However, I would look for something with removable stepper drivers since this can accommodate other drivers if those supplied with the board are inadequate.
For budget, if you do it right the first time, for 1000USD you will have a really good printer. And if you look closely and have patience you will be able to build it for quite a bit less, if you use second hand linear motion components. They sell quite a lot of them on eBay for next to nothing, and this stuff will not wear out to an extent that it impedes print quality.
Good luck!
Regards
Oscar