1. Yes, they all have similar lost towel policy.
2. There is not a "main dining room", with freestyle you choose where you want to eat and when. There are 10 dining room options. 5 included and 5 more that require a sur-charge ranging from $15. - $20. per night, per person.
3. I'm shocked that you found the entertainment lacking on RCCL, especially on a Voyager Class ship. The entertainment choices on most of the mainstream lines is comparable. I wouldn't say one has more or better than another since all such comparisons are each passengers opinion and preference. I'd rate NCL, RCI, CCL and PCL all very good, but they will vary on specific ships/crews/sailings.
4. The balcony cabins on Pearl range from 162 to 167 sq ft in the BA to BE Categories with a 38 sq ft balcony. The VOS E class balcony cabins are 173 sq ft + 47 sq ft balcony. Their D class balcony cabins are 202 sq ft + 50 sq ft balcony.
Hope this helps.