KE miles can be used on Skyteam partners and Alaska Airlines, and I think these can be used for one way, although the KE website isn't clear. KE does have the easiest lifetime status, after 500,000 miles on any Skyteam carrier you get lifetime Skyteam Elite Plus which includes lounge access.
An alternative would be to credit to Alaska, which offers one way awards -
http://www.alaskaair.com/as/mileagep...sUSACanada.asp - and Q class would earn you 70% -
http://www.alaskaair.com/as/mileagep...ine.asp#korean. Alaska has a lot of other partners your friend could also credit to Alaska.
I don't think KE has sign on bonuses - that's very much a concept in the US and a few European airlines. I haven't heard of any Asian airline offering sign-on bonuses to their program.