Looking at dates, the only 3 day weekends that I have available are:
21 - 23 May (Buddha's birthday wkd)
5 - 7 June.
At the moment, i'll be aiming for the 5 - 7 June as I think there might already be plans underway for the earlier weekend.
With regards to the route, i'll just be going one way. Was thinking of leaving Seoul first thing Friday morning, arriving in Busan Sunday afternoonish then having a wander around (i've never been to Busan so would like to see a little of it!).
Or, could do Seoul - Geoje?! What's it like there?
To be honest, I could go either way.... will have a longer think!!
You can put your bike on the bus - i've always just tied mine up to the posts etc in the boot of the bus and it's been ok.
By the way, the TDK starts on 23rd April and ends 2nd May