Pete, you have the general picture accurately. The FS system for self-belay is called the "4-inch tie in". The idea is that there is a bole diameter in most western conifers that is pretty immune to breaking out from the effects of a climber above that point...i.e. 4 inches. That's your minimum diameter to consider a bomb proof anchor point. Some species, or in some conditions, you'd elect to go bigger, but never smaller.
So you climb by whatever combination of techniques is appropriate to that bole diameter. You have taken with you your 4-inch tie-in system...usually about 40 feet of 11mm fully dynamic climbing rope, about 6 slings, each with a triple action biner, and a prussik loop.
Under a whorl at +4 inch bole diameter, tie off one end of the belay rope around the stem, throw a prussik on it with the loop, and clip it into the center point of your saddle with a life support biner. Tie a good stopper knot on the other end of the belay rope. Advance the prussik 3 feet or so up the belay rope.
Climb no more than 3 feet, place a sling in a basket hitch above a whorl, and clip a tri-act biner into the legs of the sling and run the belay rope through the biner. Make sure you've advanced the prussik above the biner. Descending, never forget to bring the prussik down with you as you go, otherwise way too much slack developes for adequate protection.
The 3 foot figure keeps you from exposing yourself to a fall of over 6 feet, per OSHA.
Repeat until you run out of tree
. If you break the top out, you won't enjoy it, but you also won't hit the ground. I personally know of two real-life instances where the climbers insist that this system saved their lives when the tree top failed under them while picking cones.
Use a lanyard to assist positioning, and to free your hands to install and remove the self-belay protection points...but always remember that the lanyard does not protect you from a fall if you don't have the self belay in place and you break out the top you are lanyarded to. Once above the anchor point, never disconnect the belay system from your harness.
You can do a similar thing with your DRT system if you need to climb above your tie-in, but you need to rig a sling to keep your life line in it's crotch or on it's limb. Excess friction can build up pretty quickly as you add protection points, and make it much more difficult to work in than the 4-inch tie in, but it's a good trick to have in your bag.