You can indeed charge them as 10s as long as you have a charger that will do 10s.
You should not leave Lipo at full charge for any length of time as it will shorten their cycle life.
They are best kept at 3.8 volts per cell and charged just before using.
If you stop discharging them at 3.7 v per cell you will fint they dont need balancing very often although you should use a cell checker every time you charge them just to make sure they are not going out of balance.
I use Multistar 16Ah batteries set as 2p3s and bulk charge them to 4.1v per cell and stop discharging at 3.7v and have not had to balance them for the last 30 charges so far.