Hello,
In order to set your skin, you either need to make the skin default for all users, by going to your Admin CP > Styles Admin > Menu or you can install it but users can select their skin by going into their User CP.
To protect certain forums, you need to set permission masks, instructions on how to do that are located
http://kb.forumer.com/index.php?article=50
The difference between phpBB2 and 3 are major, an example of a phpBB3 is
here. Firstly, Limez and his developers need to create a system that will upgrade their forum at their own discretion, so you don't have to upgrade.
For the chat., you need to pay for it with fBucks.
If you go to your admin cp > fSettings then you will be able to purchase fBucks for your fChat.
Hope this helps.