The Elise uses 4 lug 288mm rotors, so they will not fit (the hub dia. is also smaller). The front spindles, rear calipers and master cylinder are the same as the Lotus. The front calipers are slightly different, with a taller mounting boss to space the them out for the larger rotors. The rear spindles (uprights) almost identical, except the caliper mounting holes are drilled further outward for the larger rotors. The Tesla uses 300mm front and 310mm rear rotors, both 26mm thick.
As I stated, the VX220 rotors are a bolt-on, you just need to get the correct diameter to match the caliper spacing.
The only reason not to use the EBC USR1070 rotors (or equivalent, as they also make cheap imported ones) both front and rear would be if you wanted to have 2 piece rotors, or to further increase the rotor size. The 308mm of the EBC ones work perfect in the rear, as the rear pads are "down" from the outer edge of the stock 310mm, and ride right up to the edge of the 308mm ones. With a simple 4mm spacer under the bolts in the front (which Elise Parts sells) the front are a bolt on as well. If you still wanted the stock 300mm in front, any auto shop with a brake lathe could trim 4mm from the outer edge for a few bucks. But the larger diameter improves braking.
The only way to correct the terrible braking of the roadster is to install bigger brakes in the rear. Other than the pads, spending big money trying to improve braking while keeping the stock specs of the calipers and rotors is a waste.