So is it cool if I register using my NXT address from my online wallet at myNXT.info?
Can someone answer this question please.

I think mynxt.info doesn't have asset exchange integrated yet so you won't be able to geht your tokens.
I think this answer is correct. I have a mynxt.info wallet & I can receive assets to that wallet, but I can't access them using mynxt.info, so I can't sell or transfer them. If you want to trade your Kora tokens it is better to create a new account using the official NXT client IMO. I'm confident mynxt.info will add NXT AE capabilities soon, but we can't guarantee that.