I have a few questions about National Guard retirement when you go OCS (see below for details) . What pay will I receive at 20 yrs?

Ben your years as enlisted and officer all count toward your 20 as long as each year is considered a good year. The higher the points the higher the rank the better the retirement. If you’re going officer you’ll wanna get to at least Captain or above. If you look at examples under the calculator under the HR site that your CAC card allows you to access you can find out how the math work as an E-8 vs an O-2. As far as memory serves successful service after three years at any grade after 20 years service would qualify you for reserve retirement. Be sure you have all your paper work straight especially your 20 year letter and your DD249? Points sheet. I e met numerous prior senior NCOs that went onto become Officers. I strongly encourage you to keep hard copies of all your paperwork. I once met a Guard Colonel with 30 plus years service but his paperwork was messed up on the Guard side. He only had credit on the reserve side for three years. He was working in fixing the issues. Ultimately even the Guard becomes a part of the Federal Reserve by age 60 in order to get the Federal Retirement benefit.

It's been a while but if I remember correctly, you have to serve as an officer for 10 years to retire as an officer. Otherwise you revert back to your last enlisted rank. I remember this because as a First Sergeant I was offered a direct commission to 2LT but after looking into it it didn't make sense for me.

There is no TIS requirements for Guard Officers. You need 20 good years. The pay method should be either Final Pay or High 36, which should be close anyway. You final retirement pay will be your Pay Grade for your TIS (including any Gray Area time) based on your total points divided by 360x2.5%