Hi Leslie,
Congratulations on a nice scope purchase.
Re Focuser:
I am not certain about Meade, but it is probably similar to my skywatcher DOB focuser, which has two screws on the underside of the focuser.
(May be a combination of Screw and thumbscrew, or two of the same).
Anyway, one is to tension the focuser as you suggest (the screw in my case) and the other is to "lock" the focuser in position temporarily - like if you have a heavy camera attached - (this is the Thumbscrew in my case).
Re Collimation:
There are four main things to check:
1. That the secondary is located at the correct height up the tube, ie directly in line with the focus tube.
2. That the secondary is pointing in the correct direction ie that it looks "Round" when looking down the focus tube.
3. That the secondary aligns with the central dot on the primary
4. that the primary is properly aligned with the secondary.
1. and 2. can be done naked eye, and once correct, only needs to be checked occasionally (depending on how well the secondary holds its positioning).
A laser collimator (not a laser pointer) will help with 3. and 4.
But the collimator itself could be subject to misalignment of the laser and so many people don't like them.
A chesire is generally regarded as the better option by many. Not subject to collimation issues of some lasers. But these are a little more difficult to use alone.
Personally, I use a laser (that has been tested) and check it occasionally with a chesire.
IMHO lasers are easier to use in the dark, whereas the chesire is easier to use in the light.
IMHO, this is a very good guide for collimating:
http://www.astro-baby.com/collimatio...on%20guide.htm
not sure about collimating effects on pine trees.
clear skies