Yes, Joo Koon will be extended to Tuas Link. Can't recall timeline, but it was announced recently.
Stations are also confirmed:
http://en.m.wikipedia.org/wiki/Mass_Rapid_Transit_(Singapore)#section_3
Stations are also confirmed:
http://en.m.wikipedia.org/wiki/Mass_Rapid_Transit_(Singapore)#section_3
Any MRT link to Raffles Marina? Cos I saw a big bore in the ground on the land
near it, big enough to fit a station.