It'll help on the highway for rolling resistance and rpm's but will slightly hurt aero. You should see a slight gain. If you get racing/performance wheels they might not be heavier.
The new wheel set should not raise your car an inch. If you're concerned about it you can buy 2" lowering springs on Ebay for $75 (plus an installation/alignment). It will improve MPG and make the car more fun to drive!
The grille blocks look great on that car. Too bad your 14's are 4x114.3, or I might buy them off ya.