Okay lets try and answer these easily.
If we install it we install it with permissions set so that you are ready to role. You can then create your categories prices and open it up. I will have already configured all the base options etc which you can change at any time.
Well we can install it with the forum on another server if the forum on that other server allows external mysql connections. Also if your using
vb on another forum you can not use the enhanced integration since the applications are not on the same server. it is always best to have them on the same server and as wel if you want them to be integrated userwise the databases need to be able to interact with one another.
If you really want things seamless your best option is to install both of them on the same server and then move them later or move your
vb now and install classifieds.