That's a relatively small spinnaker for that size boat so, but I would still use at least 3/8" on the sheets, though it obviously depends on what type of line you are using. I have a 2000 sq ft asymmetric on my Catana 48 and use 11mm Endura Braid for sheets with no issues so far. If you are worried about the weight of the sheets in light air, just get a separate, single, really light sheet for those conditions. I typically go by the recommendations on the New England Ropes web site:
New England Ropes - Line Selector
In terms of rigging it, I would recommend an eye (or maybe a loop on a cleat if there is one far enough forward) on each bow with a block attached. Then run two tack lines, one running down the port side, through the block on the port bow and to the spinnaker tack, the other doing the same thing on the stbd side. If you have each of the tack lines on their own winch you can position the tack anywhere you like between the two bows just by adjusting the lines.
Mark.