Pot time, working time, pretty much the same thing. Remember mixed epoxy in a container will get hot fast. That same epoxy spread out cannot develop heat as fast. So to extend pot or working time, spread the stuff on a surface and take it from there like a painter uses a palette. Make a practice batch and pour some in a dixie cup. Spread the rest on a paper pie plate. See how they cure at different rates. The cup will even start to smoke. (It's not real smoke) When I said 10 minute pot life, I meant the lump of epoxy in the dixie cup. That's the "worse case" scenerio. Same is true for tropical hardener. Maybe 2 hours in the dixie cup and could be 4-8 hours spread out.
You can add layers of glass or CF as soon as the first layer is set up. No need to sand between layers. This will only result in very clogged sandpaper as the epoxy is firm but not really stone-like. No problem with adhesion between layers. But do not go more than 48 hours between layers with WEST SYSTEMS or you will have to first wash the surface and then sand. The reason being the curing epoxy releases a chemical called "amines". I could have the spelling wrong and really don't know what the hell amines are. All I know is that they form a water-soluable top layer that is greasy to the touch. Almost like someone rubbed baby oil on the surface. And it has a strong chemical smell. This greasy layer will mess up further layers if you do not remove it with soapy water and then roughen the surface with course sandpaper. This should never be a problem if you simply do all your layup work in rapid succession.
Linear stands can be arrainged at your whim. It's the epoxy and how long you take between applications as mentioned above that is important. You always want previous work to stick to later work. If you have to wait long periods between epoxy application just wash the old work and sand. It's those damn amines that slowly work out of the epoxy you have to be aware of. If the thing you are making is done all in one shot, as in vaccum bagging, amines are a moot point. (unless you plan to paint the surface - then treat painting like another layer of epoxy: wait 3 days, wash, sand, paint)
You are exactly correct about vaccum bagging. It's the best way to control the exact amount of resin going into a known area of composite material like glass or CF. A good layup man working by hand can equal the quality of a vaccum bagged product. But there are damn few good layup men around. (Now for some shameless self-promotion) I was the first person to use vaccum bagging in commercial kayak construction in the US and probably the world. That was in 1978 about 5 years ahead of most other makers. I went to VBagging because I could not find workers who could do hand layup work of suitable quality. At first I held my nose at the notion, but in time came to realize what a good thing it is. The technique was taught to me by an engineer I hired from the aircraft industry. I did not invent VBagging by any means.
Hope this in some way helps.