Yes, you will get to use the lounges. SQ is not stingy when it comes to service, in fact most of my friends in Asia have cannot grasp the idea of "club membership" which is very much an american thing (as is curbside checkin... I only see this in the USA)

I'm a big fan of rows 15/16 on the A340. The FA's will always pin shut the curtain between Y and J, and the second section offers more privacy IMHO.