Correct. If you do not fly for 3 months, you stop accumulating gate months in the 4th month. Sims don't count.
The wings are based on 3,000+ hours and >15 years of aviation service. As long as you have a current AO for 15 years of time and 3,000+ hours (or 15 years on AOs and 2,300+ hours with 144+ gate months) then you get the toilet bowl.
You get your first set of AOs when you graduate UPT.