No, the E-7 is not the same as the E-4, but it isnt much different either. The E-7 was based on the E-4/N, which had a 1,200 hp engine (as opposed to a 1,175 hp engine on the E4). It had an under-fuselage hardpoint that could mount a single 250 kg bomb, or 4 50 kg bombs, or a 300 liter drop tank.
I'm not so much concerned about the DT for the scenario (as it would be easy to tell people not to load it, and I think most people would abide by that), I am concerned because without it the 109E won't really be a viable choice in the MA due to its very restricted radius.
There were no other differences between the E-4, the E-4/N, and the E-7. If people are concerned the extra 25 horsepower will unbalance a BoB scenario, then model the E-7 with 1,175 horsepower.