Power emission and compatibility.

generally, a weaker power will result in a shorter range.
For indoor flying, you don't typically need more than about 1mW. For park flying, 10mW is generally sufficient. For longer range, 100mW or 150mW. Note that 150mW wll not provide a lot more range than 100mW but it will consume batteries a lot faster. battery life will be longer with lower power, and you won't cause as much interference.

sorry, I didn't understand your 2nd question when I 1st read it.
You can use Devention with the diode mod, butyou will be locked into 15mW mode. This will drain your battery quicklyand is too much power for what most people use their devo7e for. It is rude to any fellow flyers to use full power if only flying in a park/indoor. In theory a 150mW signal can control a model 1500m away or more (though I've never seen that kind of range myself)

The devo7e is not a devo10 in harware. you can't run the devo10 firmware on it. Deviation allows you to bring out everything the Devo7e can deliver. It also allows mods like additional switches/modules. Because of hardware limitations, there are things it cannot do, that the Devo10 does (basically it doesn't have enough memory to hold the code for all the features we've developed)