If I have another FAA CFI available, can he do my BFR in a non N-Registered airplane.
Also I have all the requirements for CFI renewal. Have successfully given more than 10 sign offs within past 24 months with more than 80% passrate. Do I have to be present in US to get it renewed or it can be done while i am physically in my own home country.
There is no requirement to have a N-registered airplane for a flight review.
You do not need to be in the US to renew your flight instructor certificate. Do it online. You can do it with proof of your instructing records, but you can also do it with a refresher course online, too.