Can we accept cash from donors for orphanage having fcra, 12a and 80g

I am venkat from chennai, just started orphanage 15 days back,  Entitled FCRA, 12A and 80G. when people are visiting orphanage they offer cash instead of card and cheque payment. My questionS are below...

Can we accept cash ?

If accept, how much we can accept ?

If we accept cash, can we deposit the same cash at a time in orphanage bank home branch ?

if not, what shall we do because they are willing to give cash but not card and cheque ?

is there any alternative sources under law for accepting cash ?

Please provide your valuable answers for running orphanage smoothly...