Two comments:
1) Skip Bombing...
Quote from "12 to 1, V Fighter Command Aces of the Pacific":
"...When using a bomb load of only one 500lb'er slung under the belly, my approach is a shallow dive at about 370mph, levelling off at around 50' and letting her go..."[P-47 pilot]
It wasn't a special bomb that allowed them to skip. The fuse was a 4-5 sec. fuse so when the bomb impacted, it didn't go off in their face. It was a GP bomb. While it may "skip" when it hits the ground, the fuse and delivery angle is what works the magic. The same technique is called "lob bombing" today. Watch some video footage of the Argentine Air Force going against the Royal Navy during the Falklands. You'll see some excellent examples of what would have been called "skip bombing" in WWII.
If you've got a different source, I'd be happy to learn something...honestly. I can provide more if you need...
2) Para-Frags...
Para-frag bombs exist to create drag on the bomb, that's it. They aren't parachutes designed to let a 250lb (or bigger) bomb "float" to the deck from 25K. All they did was slow the bomb down just enough that it impacted behind the delivery aircraft, clear of the frag pattern. Accuracy wasn't really an issue, since they were typically used to crater runways. Most delay fuzes were used for the same reason--cratering runways or allowing the aircraft to avoid its own blast. If the length of delay was limited to 5 seconds or less, it wouldn't throw game play all out of whack. Plus, you limit it to bombers that actually conducted low level hits in WWII, like the B-26, A-20, etc. I guess I'm not thinking like a Aces Quake player--I can't imagine a way to "game the game" with that type of setup...Coding it, is an altogether different issue...