For intimates, the limo must be used four hours in a row. Like you said, if you book it at noon, you have it until four. It's because you're booking the service and time of the driver, not necessarily the car itself and the driver comes in four hour blocks. If you wanted to use the limo to pick you up at the airport, then you'd have it for four hours that afternoon so go hit the outlet malls on the way in or something like that. Or better yet, just book an airport transfer separately with Mears or similar and save the limo for the big day--especially if you're staying at AKL and getting married elsewhere.
Regarding the reception, you must have it at the venue of your wedding (ie Sunset Pointe wedding, Poly reception). Having the cake boxed and delivered to Tony's for dinner that evening is absolutely possible. There are no extra fees attached for doing that, but it will take some coordination and follow-up with your EM to make sure it happens as it is certainly a special request (which they will oblige). You'll still have the "reception" after your ceremony for the sake of photos, but the cake will then be boxed in tact, minus the piece you cut for the feeding each other cake photo, and you'll then be set for dinner that evening.
A word of warning though, it is very difficult for Tony's to easily accomodate groups over 8 in number. This is experience talking. Their tables are pretty much all four-tops and we had 12 in our party. We got a PS for 12, but with their floor layout they were unable to push together enough tables for us to be seated in one long row. So we were bunched together eight at one table and four at another which was kiddy-corner adjacent to the other. Wasn't the best seating, but it wasn't our wedding dinner either so we rolled with it and enjoyed the personalities of the waitstaff.