This may be totally obvious, but after reading the rules, I am wondering if a bomber can attack 'normally' (from an adjacent territory), or if it must be performing the bombing ability in order to attack? I'm inclined to say yes, they can attack adjacently, too. I have yet to play (should get my first game in next week), but right now I'm having trouble seeing the benefit of the bombing ability, unless you gang up with a whole bunch of bombers and adjacent units. Unless you've got a lot of territories under your control, jumping over 3 territories seems too risky, especially if you're not attacking with other adjacent units- you're likely to either lose the bomber from the defender rolls first rule, or from the supply line rule. Not to mention the fact that 'bombing bombers' can't claim a territory if they're the only surviving attacking unit(s). It could be a way to chip away at your enemy and keep their numbers down, but I think I'd be inclined to use them en masse to ensure some damage was done and not lose them all to pot shots from infantry. Perhaps a good strategy is to hold off on using the bomber ability until you've made some headway and have more units on the board.
I can't imagine why you'd use the bombing ability in the 'example of a defender firing' graphic on page 18 of the rule book- wouldn't it make more sense to add the bomber to the friendly units and attack en masse from there? If there were 5 units already in the attacking territory, then, yes, it would make sense. Unless bombers have to bomb to attack…
Of course, I may get a better picture once I actually play the game.