Question on power of atterney for signature

Hi,

I want to know about scope of power of Atterney for signature.

I am having home loan in process and I have to be out of country for a month or so...

I want to do power of atterney doc so that my wife/parents can take care of my home loan.

Can anybody help knowing me what rights I give to other person when i do Power of Atterney and

can we do it for perticular period of time (duration).