Kyle, another welcome. If you're thinking of relatively casual background music listening for the dining area(while dining?)I don't think that it would be necessary to consider placing separate speakers there. The M60s should be excellent for your main listening area and provide a nice background in the dining area.
As to the sub, while I have and strongly endorse the EP500, I rather doubt that you'd be dissatisfied with the new EP350 and the budget consideration that you mentioned would suggest that you at least try it.
