Thanks for the nice compliments Melissa!
I think the only place you can not use Cindy's Carriage is Sunset Point. I know they use to let people have it at Sea Breeze Point, but I have heard something about the Boardwakl not being able to support the weight of the carriage, so you will have to check that out if you are considering that location. Also, you should be able to use it at the Yacht club if you choose to have your ceremony there at the Garden Gazebo.
You may add anything you want to your intimate but always at an additional cost. Just because you choose to have an intimate, don't think that you need to skimp on anything or that there are restrictions. Disney makes you think that there are so many restrictions, but in reality, if you are willing to pay for it, anything is possible. We added the coach and the Major Domo. Both were a little more $ then we wanted to spend, but they were things that made our wedding a true fairytale and things that could only happen in Disney, so it was worth it!
Just my opinion, I didn't think it was worth it to upgrade my cake. If you wish, you may want to bring your own topper if you don't like the Minnie and Mickey one, but the cake wasn't a big deal to us and we thought the one that Disney offered was just fine. And it tasted very yummy!