Various Questions: Which Cpanel Tree To Run - When To Update - How To Troubleshoot..

I have a zone.net VPS with 1152mb of RAM.

I don't resell, I am using the VPS for personal use to run a small vBulletin board (30-60 members on at a time), a Mambo site that is used to aggregate news (12,000 or so news items), and then a couple small personal static sites, and about 25 email addresses.

My VPS has the following versions listed in WHM:

WHM 11.11.0 cPanel 11.15.0-R17853
CENTOS Enterprise 4.5 i686 on virtuozzo - WHM X v3.1

It is currently setup with the default update settings that came when Zone.net set it up, which are:

cPanel/WHM Updates = Manual Updates Only (STABLE tree)
cPanel Package Updates = Automatic
Security Package Updates = Automatic

Question 1:
So, for the type of site I am running, is the stable tree the best? While it is a small vBulletin community, lack of down time is my main goal, so I need to balance getting updates fast enough to keep it secure, but not getting 'bleeding edge' bugs introduced. Which tree is the best balance?

Question 2:
Should I be running automatic updats on cPanel/WHM or keep it manual and check here and other forums for important updates?

Question 3:
I recently had a problem where Horde stopped working. Zone.net's support staff helped me, and suggested two things to attempt to fix it, and this "/scripts/fullhordereset" fixed it. So, since I am new to VPS's and more specifically, working with Linux, how to I learn/research things like this in the future. Should I be checking out forums/communities for each individual app (like Horde), or is there a better option?

Question 4:
Unfortunately, I don't know what I don't know. Such as what tree to run, when to do cPanel updates, when to do Apache updates, how to make sure all my configs are right. Any suggestions on how to both make sure my WHM is configured the best way for my purposes, and more importantly, what is the best way of moving from WHM