Would you have these questions if offering an Ecom solution?
If no go with OS2 if yes than linux is a reasonable decision. My first rule of thumb on hardware is buy it from some place who does house calls for warranty work and who lives close enough to physically beat if something breaks. Get the main outfit working then the sattelites. Nightly dialup reconciliation should be fine. Daily Incremental backups after sync and weekly full backups being taken offsight for DR. I like [link|http://www.arkeia.com/|http://www.arkeia.com/] for backups but others doing daily linux archiving will have current suggestions. On rates find out what going rate is and go under that. Ensure that it is hourly but give a good faith estimate of time involved in writing detailing what is and is not included. This will save hard feelings later. Try to build a cushion into the estimate so you are secure that you can meet or beat it.
luck,
Bill
