I think that sub-forums within the infp area would generally be a bad idea, because every level of depth tends to have less footfall. This means that people won't be searching through every sub-forum regularly andone of the things I like about forums is how threads you didn't think you would be interested in surprise you.
Stickies are also generally a bad idea, because people start to ignore them. Like anything they become old after a while, and it reduces the number of other threads on the page. If they are active enough to be stickied then they should be active enough to keep coming back to the front page, and the software here does a good job on providing notifications to people if shouted out or quoted to keep a conversation going even if the thread has slipped back a few pages.
Instead this should be replaced by an index system. There is one that has been started, but I guess there is no time for that mod to keep it up to date. The first job of the mod should be to index all the stickies and then release them. I'd personally organise it as:
Resources (because many INFPs first come here as a journey of self discovery)
Advice (for all the inspirational threads telling infps they don't suck)
Popular (for all the threads that are dozens of pages long, and an important part of infp perc history)
Hot! (for new threads they are getting a lot of attention)
The index should have the thread title as a link, and a brief description of what the thread is about. That will allow you to release the stickies.
Another sticky that I would have is an introduction thread, called "Are you new? If so read and post here!". The top few posts will contain some brief chatter, and introduction. A brief explanation of some of the rules and mannerisms of posting, and a request to say hi in the thread. This will let people new here get up to speed on what is going on. It should also encourage lurkers to sign up - I lurked here for a year before registering an account.
I think the only other sticky I would have is a rant thread. The rule here is that nobody is allowed to offer advice. People sometimes just want to shout at the world, and the last thing they need is other people making them look stupid by offering good ideas or concrete advice, or pointing out why they are messing things up. People can respond of course with supporting messages, becomes sometimes you just want a hug.
If the software allows I'd auto lock any thread more than 3 months old. Because sometimes it is good to start a new thread on something. If a conversation gets to 20 pages long, is exhausted and stops then it can be hard to find new ground because things have becomes established. Often with a new thread things will go in a new direction, if nothing else then because there are new people. And the conversation can be worth having again even if it just rehashes what has been talked about before, because often the journey is as important as the destination.