I think it you actually asked a question, per question, instead of grouping them all together it would be much easier to give you the information you require.
Like with the USB HDD. Okay you want to backup the servers. You want to backup the SBS08 box as well as the TS box. How are these going to be configured? Do you want to have it setup so it will backup as one job? Are you hoping to just use the built-in backup utility or you looking at using other software to do the backup. Are you going to be using mutliple rotating backups? How often and how much data are they going to be backing up.
By having specific questions it makes it so much easier to give you an idea of where to start.