Of course, you won't hold all of the "mass" you gain on cycle, but thats because some of what you gain on the scale has to do with increased fluid and this water will slowly drain. But as for real muscle gain, as long as you are able to eat enough, I imagine that at your size, you should be able to make it work. You might not be able to hold the same look. Steroids are going to ensure that you are directing your food toward muscle building much more than fat gain and when you come off, more food may lead to more fat. So it's going to be a balance. At 45, you do qualify for HRT is your test levels are naturally low. If you have been natural up to this point, I highly doubt that is the case, but it would still be a good idea to know where you stand. This way, you can get tested post cycle and know what normal is for you and you will know when you have recovered. Then if you did qualify for HRT and wanted to use test replacement, you could skip PCT and stay on year round and much more easily retain your muscle post cycle. Thats a big life decision though and a whole other topic. 

As for your questions, 1, I don't think you need the Var. Save it for your cutting cycle.  2. Covered already. 3. PCT is fine. 4. I would wait to start your new cycle once you have recovered. PHs are steroids and will shut you down. I would run a PCT and then wait another 4 wks. It wouldn't hurt to get your labs done before you start to make sure that your liver and cholesterol has returned to normal