If your asking if you can take a 3mb and 1.5mb connection, bridge them, and then download a file 4.5mb speeds, no. You can use both connections to load balance though. Look into dual wan routers and see if they do want you want.
I've got no idea how it says 4 computers. The only ones im folding on are my server and my main computer. It could be because I keep switching os's on my main computer and then folding, so it thinks its a different computer.
Yea thats what I was thinking would be kinda nice, if something goess baad you don't have to rma it like with most online stores, you could just return it.