Yes you can connect the top and bottom sets with two short lenghts of speaker wire. As far as which posts to connect your speaker cables to you'll have to try it both ways and listen. Perhaps call the manufacturer of your speakers and ask what they'd recommend too. When I've done it both ways I've tended to prefer hooking the speaker cable to the top posts and jumping to the bottom set.

Several speaker cable manufaturers make jumpers as does MapleShade. I would try to use jumpers of the same quality of your speaker cables. I do bi-wire my speakers.