[Suicide Junkie]

-Race specific technology

What exactly do you mean? SE4 already has racial technologies...

-Increase the size of the starship graphics. Allow dreadnaughts, starbases, baseships, etc to take up more than one square in combat. Now their size matters.

Realistically, you should be able to stack a whole lot of ships in one combat square as in SE3.
Turning, movement and targetting would all become problems for multi-square ships.

Are you looking for a coordinate-based system instead of tiles?