Pins and needles usually are due to irritation of a nerve. If you are doing hand stands regularly, this could be the cause. I recommend stopping, lots of bad neck issues will arise. If it continues, get evaluated before it gets serious.

Sounds like a pinched nerve somewhere. Might need medical attention.

Not enough info. You need an evaluation to determine. See your primary care.

Depends if new or all the time and also where the tingling occurs. If you are in an extreme range of motion is used then sometimes the nerve is just getting pulled to tight. Other option is “VARIABLE” genetic make up of muscles and do the pinch the nerve by certain positions compressing the nerve!