H1B Transfer Profit - NonProfit - Profit

Hi I am on H1B visa and working with “CompanyA” which is a Profit organization since 2009. I have EB2 i140 approved with priority date in 2011. I got an offer from a Non-Profit organization “CompanyB”. Just want to know if i should proceed with it or not. I have few questions.

As I am already in 8th year of my current Profit H1, Is it possible to get new Non-Profit H1 on the basis of Approved i140 (with a Profit Organization “CompanyA”)?Can i start working with new employer as soon as i get the H1B filing Receipt or I should wait for new 797 approval?I know the New employer (Non-Profit CompanyB) have to file i140 again, is it possible to get the keep Priority date from previous one?Is it okay to travel abroad (India) and go for stamping after Non-Profit H1B approved or I have to wait for new i140 approval.Due to whatever reasons, in few year if I have to transfer back to Profit Organization, will it be like applying for new Profit H1 and participate in Lottery OR it will be considered as Lottery exempt?Thanks in Advance