Basically you will end up with a 4400mAh battery. and voltage will stay the sam eif connecte din parallel. Another benefit of a parallel circuit is lower overall resistance.

As for putting different capacity bateries in parallel, I have done it with NiCad and NiMH receiver packs. I was told I'd have all sorts of problems but there were none whatsoever. In fact, after flying the plane I could recharge each battery and found them to both always to be drained in equal percentages. For instance, let's say I had a 1000mAh and 2000mAh NiMh in parallel. After a day at the field the both would take roughly 40% to recharge. In other words the 1000mAh pack would take 400mAh to recharge and the 2000mAh would take 800mAh to recharge. These numbers aren't exactly what I got of course, I just used them for demonstration since they are simple. I checked this on numerous occasions and always found the batteries to be drained in equal percentages. Now, the batteries were the same cell configuration and from the same manufacturer. Both always fully charged using the same charger.

I didn't need any diodes, special circuit boards or anything else. What would have happened if there was a major cell failure in one pack? Not sure but I fifgure I'd have issues if that happened regardless.

This was with Nicad and NimH now... Lipo's may or may not be the same. I don't know enough about them to say either way.

When it comes to mixing c-ratings in a parallel battery circuit, I have no idea on that either.