
1, I decided to play with only passenger vehicles (because the sheer number of cargo vehicles is overwhelming for me!). So I set the available vehicles parameter to "Only passenger vehicles". My thinking was that I'd have the passenger vehicles from eGRVTS and just use the cargo vehicles from the vanilla game. But setting the parameter this way actually seems to completely disable all cargo vehicles from the game (including the vanilla ones). So it becomes impossible to transport cargo at all. Is there any way to enable the eGRVTS passenger vehicles whilst keeping the cargo vehicles from the vanilla game?
2, This is a more broad question about vehicle NewGRFs in general. All the vehicle NewGRFs I've tried seem to actually 'overwrite' the vanilla vehicles. In eGRVTS for example, the eGRVTS buses are added, but the vanilla bus is taken away. In FISH, all the new ships are added but the vanilla ships are taken away. This might just be a fundamental aspect of the way NewGRFs work, so sorry if I'm misunderstanding. If not, is there any way to simply 'add' new vehicles from newGRFs to the overall pool of vehicles, rather than 'replacing' the original ones?
Sorry for the very newbie questions, I'm just trying out GRFs for the first time. I love all these vehicle GRFs, I'm just unsure whether to keep using them because they all add such a large number of vehicles! Can get a bit overhwleming for me in-game. Not to mention that I don't know how to 'save' window sizes - every time I open the 'New Vehicles' window, I have to enlarge the window so I can see all the vehicles. Then the next time I open it, it has shrunk back to minimum size again. Actually, let's make that a question number three!

3, Is there any way for the game to 'remember' your resizing of windows (particularly the New Vehicles window), so you don't have to resize it every time you want to buy a new vehicle?