>1) Is it a problem (performance) to have a big number of views in a
> database?

Not really. How many do you propose to use? The more objects you have, the longer it will take to open the Database Designer...

>2) Is it useful to do all access to data via views, to keep the
> ability of using remote data in my application?

IMHO, views are better to use as a better separation in data is achived. However, I would not rely on remote views to access remote data. At the very least, I would not use the remote view as the basis for updating. Rather, I may use the view to display, but share the connection and use SQL Pass Through. Then again, based on pending improvements to the product, I would use ADO instead... But a combination of views and SPT is something you could implement today..