I'm sure I will be hooked once I get down there. I don't think I will ever stop snorkeling though. It's so easy to just jump in and look/see. There's a lot of work getting dive ready!
It might feel like that right now, but really, diving Coz is almost as easy. It'll be much different than doing checkout dives in cold water with bad viz. Your tanks and weights will already be on the boat. I don't know if there are gear lockers close to the dock or if you have gear, but that makes things easier. If you're renting equipment and diving with the house dive op, you'll walk out of your room with very little weight and get on a boat where your gear will probably already be set up on a tank. The boat will pick you up after your first dive, right where you're floating. You'll probably be told not to swim to the boat. Your 2nd tank will very likely be switched out for you, likely before you're even aware you're back on the boat.
deepsea21 said, "I may be wrong but after your first day of diving in Coz I bet you are going to forget about the snorkeling and want to dive all you can."
I had the same thought. You know you, and 3 days might be just right for great reasons. I liked snorkeling and still do, but once I started diving it felt like, if I'm going to this much effort to snorkel, I'd just as soon be diving. It's more money, of course, but really very little extra effort if any. For some, I'm one, it's very hard to sit on dry land knowing that you could be diving.
If you get down there and decide that 3 days isn't enough, it probably won't be very hard to get a spot on a boat with Dive Paradise. It might cost a little more than a package deal, but I'm guessing it'll be doable.