1. I don't think that is possible (there is .qvw to track the memory usage of the server, but not divided by each .qvw) but I'm not sure.
2. It depends on your server settings. When you just put the .qvw on the server, it doesn't use memory until someone opens it (and it will grow as the user use it with every new calculation) and then, the memory will only decrease depending on the "session timeout" and the "document timeout" settings (in the QMC). Or, if you use the preload option, the memory usage of that .qvw will never decrease under the memory that is used to preload it because it will always stay "loaded".
3. The increase % when your reload depends ont the size of the data loaded (the .qvw size depends a lot about the size of the data) , but also on what you have in the loading script (for example if you join tables, memory will increase during the process).