Yeah it keeps it nice and warm throughout, and also nice to not have press the button, just hold the stem upside down like it's a pipe and then the TP80 becomes like your lighter! I turn off the cruise whenever I want to and restart it as needed, not always necessarily the most battery efficient (make sure you have eco turned on and set to 1 though to help that), but I have plenty to swap so that's not usually a concern of mine...
Yes you have to keep holding down the button to keep the heater activated, unless you are using cruise (that is what Cruise is, holding down the button for you!) It is less like you are in on demand mode, basically if you press and hold down you are activating the heater, or you can press twice to go into cruise without having to hold it down... Using on-demand mode, without keeping tetra on top upside down and removing it to clear a hit, I would let go of the trigger before I finish inhaling so I can clear the hit that way instead, if that makes sense?
When you say rod, do you mean glass stem? The old plain long bent stems are great, and the old long custom spiked bent stem, but I don't know if those are available anymore so the short spiky bent stem is also pretty great!
I have not tried the tank yet, but I find the nub not so useful with my tetra personally (I use it with RBT Vapes instead) amaze cooler is really great, but I don't like the wood stems really because of the capsule...
I also have the mini j-hook which is fantastic, but mine is the older female style, I am sure the new male style are also great though!
With a WPA you can use any j hook, I have quite a few now, really that is the best way for cooling in my experience... Very comfortable to use with TP80 upside down like I like!