Ho hum, here we go again as the search function appears to have failed again.
Dry training or SMQ(D)...8 weeks, HMS Drake (Devonport) for T boats
HMS Neptune (Faslane) V and A boats
Dry consists of classroom work and going down to whatever boat is alongside and crawling round it finding valves etc.
Wet traing (SMQ)W...roughly 3 months on a boat, time taken though depends on what spaces are available on boats going to sea and how much effort you put into it once you get there.
No idea on interview questions but try the search function.