We left all kinds of stuff on/under/around our chairs and never had an issue.
We actually left our camera on the table at breakfast and when one of the staff located it was returned to use before we actually knew it was missing!
We tried the walkie talkies but found it didn't work well for us. We wanted to keep track of the kids (pre teen) but found that they couldn't keep them with them if they were in the pool or using the slides (which it seemed they always were!!). For us it worked better to get some waterproof watches for the kids and give them time they had to check in with us. Every 15 min or 1/2 hr. We would walk over and check on them once in a while as well.
As for the grounds - we didn't find it too bad at all. We ended up staying in the same area most of the time as we are not "beach" people. Only went down to the beach for the banana boat rides (fun fun fun!!) and to visit the vendors (not much there - found better shopping on the resort as they invite different vendors in each day).
Have a wonderful trip!!