In order to solve the charging issue FullspeedRC (yes the same ones that launched the Leader series of micro quads) have released a simple board that allows the batteries to be balance charge using the existing USB port. It can be bought for around $10 at the following retailers:
Please note this is not a beginner install but if you can solder a FPV cam and vtx to a flight controller you can probably do this. I've put in a LOT of photos and steps in below to make it as straightforward as possible since Fullspeed's manual is accurate but overly short. As usual click any image below to embiggen.
Tools I recommend for this job: