I will be going to Korea in May. Thought of buying a SmartPhone there. Will it work in Malaysia?

I remember I had my old Nokia 5800 while I was in Korea back in 2012 running on Maxis PrePaid. I was able to receive call from Malaysia.

You are probably right. But I am aiming for phones that you cant buy here, those with unique design that is not common here in M'ysia. Maybe a clamshell?

Yep, I've done it before. I did so via maybank. Had to visit the counter and fill up a form plus additional charge for the transfer. The detail that you need from the Guesthouse owner are:

1) Their bank's SWIFT code
2) Name of bank
3) address of bank

and make sure to tell the bank that you will bear the transfer fees.

Yes, with that details you can go ahead and transfer it to any banks in Korea.
And no, I do not think you can give Malaysian Bank the Korean Won and ask them to transfer it. In fact, while I was transferring my cash to a bank in Korea, the bank had to convert it to USD first and then transfer it to the Korean Bank.