is it OK for the battery if you keep using the tablet while it's charging? And should you stop charging when it's fully charged.
Yes, you can use a tablet while it is charging. But, if you do something cpu intense (like 3d game) it can become a little hot.
No, you don't need to stop charging when fully charged. The tablet will make sure you don't overcharge.
It's advisable not to play graphic intensive games while charging, the cpu and graphics chipset gets hot which is not good for a long run meaning decreases longevity of the device.
Please disconnect the device from charge after a full charge i.e 100%, good for longevity of the battery.
To further increase the longevity of the battery you can keep charge cycle of 10%-90% or 20%-80% every time charging the device and give a full charge i.e 100% atleast once per month. P. S - Number 3 Point only if you want to be extra careful with your battery. What I always do and is normally advisable never let battery go below 10% and never leave it charging once it says fully charged.