I will suggest you to execute two power of attorney to avoid any legal complication. One by you and one by your wife.
The stamp paper required is Rs 50/- for it however on safer side take the stamp paper of Rs 100/-. (nothing else is required)
1. You can take put the printout of the attorney on plain paper and get it attested in your country. Then send it to attorney and he will attach a paper of Rs 100 and get it notarised. It's ready for use
2. Get 2 Rs 100 papers from india and take printouts of both attorneys and get it attested at your place. Send it to attorney and he will get it attested in india. It is ready to use.
Since power of attorney is not transferring any property to attorney holder so only this much stam duty is payable.
I guess your queries have been resolved as there is no major expenses in giving POA. Give attorney to whomsover you want. It's a cheap process don't worry. Just make sure you give proper attorney or you may be asked to reframe it, which will consume more time and effort. Get the attorney drafted from a lawyer and save hassles.