I will try to answer a couple more questions. The limb walk, returning from, like Tom says it is not a lot different from doubled rope, but it is different enough.
On returns where your tip is high enough, you will come in just like Kevin said, using your rope more like a handrail. It is slightly different than doubled rope because you don't lean against the rope quite as hard.
On those really hard, downward sloping limbs, where you have to wedge your foot into a crotch and then lean out and down, I have found no other way to get back out than adding mechanical advantage to the system. This is where I will clip a pulley to the line and run the tail over the pulley and the Unicender is then in a RADS configuration. This allows a 3:1 advantage. Much easier than coming up on a doubled rope and when you are back up into a good position, easily clips off and hangs on your saddle.
If you are using the Unicender on your bridge, it will self-tend the slack as you walk in.
For most situations redirects are just so easy that most of the time you will be able to acquire a better angle,thus not having the difficulty factor on the return walk.
I use single rope for all trees, including removals. I just choke off the line on the stem leaving the tail on the bowline. It is really quite simple.
I hear many say they only use single rope to access large trees. But the same energy expenditure is used whether it is a 20 ft climb or a 100 ft climb. You won't be out of breath in the 20 ft climb, but the energy expenditure is there.
One more thing, and this might belong the other thread on safety, but when doing large conifers where your access line is close to your work area and convoluted and not easy to see, just go directly to your tip and reset it to the outside of the canopy. This takes a little more time, but is well worth it.
Dave