It certainly is.
Create a new group and add the members who want to access this area in this group, but leave them in the Registered Users group. Next create a new forum and give your new group "Yes" permissions for that forum and give the Registered Users group "No" permissions for that forum
Why are some people prone to premonitions instead of replying after they carried out actions (unbound to having succeeded or failed at it).
Not a good idea "long term" as it is probably going to be dropped in a future version of phpBB
It's a form of courtesy, aknowledging that someone's help is appreciated and advice will be followed (or at least taken into account). Trivial things like this are essential (personal opinion and generally accepted in decent circles ) in life.