Training camp is open to the public on most days. It's very fun, especially on the first days when there's tons of fans. You might also get lucky and get to see a scrimmage like last year.
My recommendations are to bring sunscreen, sunglasses, a cap, and plenty of water as it is smoltering hot.
Also, get the number of the weather hotline for training camp, as one day when I rode the bus for an hour just to get there on a cloudy but not rainy day, practice got sent to the bubble, and I had to spend another hour on the bus back home
I recommend staying around Las Olas Beach in Fort Lauderdale. Its around 20 minutes from training camp. Aside from the beach, there's not much to do in Miami. If you have kids, I recommend Wannadoo City at Sawgrass Mall not far from Training Camp. There, its a theme park where kids can do different jobs. Sounds stupid, but kids up to like 11 or 12 have a blast.