Do I have to have XEM coins in personal wallet to receive same amount of new SYM coins? or can I just stay on the online exchange and receive the new SYM coins?
I think it would be a good idea to have Your coins in a personal wallet. Then You can choose to opt in early or wait until later. No exchanges have said they will do the swap for their customers, and since it is opt in it will be very complicated for them to do so.