I think you MOSTLY have it. Sorry, my earlier post would have been more complete, except I had to suddenly take a journey to visit a friend who I don't get too many chances to see and had to close quickly.
First, this is important for you to know all the way around, however, in this case, it will cover the bulk of your questions. It comes from:
Crew -- Global Wiki
This is linked to show up at Crew Management. Most of what you should know to answer these questions are in there.
You have a tank. It has to have a crew. You recruit said crew and train it FOR that tank. This is the normal Tech Tree way. If you move your crew to a new Tech Tree Tank and Do Not Train them, they operate that tank, even of the same class, at a penalty. When you spend 20K credits per Crew to Regimental Training, they will be 75% Crew (if new) or, 90% of their Previous Qualification (if your crew is under 85%, you might as well get a new crew when paying credits). This is for a Tank of the Same Class. A New Class the above number drops from 90% of their previous qualification to 80% for credits.
If you train with 200 Gold per crew, they train to the new tank with full levels as if they were always there at the new tank. That's Tank Academy Level training.
This keeps going on through the tech tree as you bring your crews up from lower tier tanks to upper tier tanks. Okay, we all pretty much know that.
Now. Premium tanks can be had with and without crew. The ones that come with crew are Pre-Trained to the Premium. They are usually something like a 0 Skill BIA crew. These are probably the only crew I would immediately train to a Tech Tree Tank with 200 Gold per Crew.
Reason: Premium Tanks allow ANY crew of the SAME CLASS of tank in the Nation Line to play/train in that tank with NO PENALTY for NOT BEING TRAINED. In fact, they operate as if they are in their nice comfy proper tech tree tank, PLUS they get the Premium 1.5X along with any other things you might be running.
This is the true value of a Premium Tank. It can Accept ANY SAME CLASS Crew at no penalty so you don't have to train them to the Premium to play in it.
Simply placing, in your example, the SU-85 Crew into the SU-100Y would be fine. However, taking them from the Premium and then plopping them into the SU-100 Tech Tree Tank would still require you to train them on that tank or operate it at a penalty as described in the above links.
Tech Tree Tier IV --> Tech Tree Tier V: Train the crew to the new tank.
Tech Tree Tier IV --> Premium Tier VI: Place them in and play, no training required.
At no time will placing a crew in a Premium Tank automatically make them able to operate a Tech Tree Tank they are not trained for without a penalty. It does not rub off.
Hope that helps.
GL, HF & HSYBF!
OvO
Edited by dunniteowl, Jul 14 2019 - 00:25.