Using both local and wireless internet at the same time?

Ok, so here is the deal. I have a local internet connection with ATT as well as a connection with our free local wireless internet. The wireless internet is much faster however. I am usually connected to both of them, but it defaults to my local internet connection and will not allow me to use both of them.

Now, I wonder if any of the below are possible.

a.) I 'combine' both the local and internet so I could have a upload and download speed of both of them combined
b.) I use the local connection for certain things (browsing) and the wireless for others (downloading files)
c.) Impossible to do either of the two.