FileMaker Hosting Performance for Internet and Intranet

I have a client who has a central office with about 10 employees and 2 satellite offices with 5 employees each. They are hosting a FileMaker database on their local network for the 10 employees in the main office. They would like to make the database available to their other 2 satellite offices. They are also wanting to make the database accessible for their customers via Custom Web Publishing, which could be anywhere from 10-15 simultaneous "web browser-based" connections throughout the day.

The database functionality is fairly simple, and the scripts are not too complex. However, they would like to make files available to their customers for download (script generated PDFs and other misc files).

I'm recommending that they NOT share out their database from their office since their DSL connection would not be enough bandwidth for this amount of traffic. I'm recommending they host with an outside FileMaker hosting company. Since I've not had too much experience with FileMaker hosting companies, I have a few major questions:

1. Generally speaking, how good are the services (any recommendations...)?

2. A big concern is the performance for the main office. In general, how much slower is it to host through the internet vs. over a local intranet?

3. Does embedding/linking files in the database cause any performance issues for either type of access (FileMaker client and Custom Web Publishing)?