be careful if you are bottling since if the yeast are not done with the beer and you have a high gravity that isn't "done" the yeast will continue to chomp on it after bottling and you thus risk bottle bombs. So make sure the yeast you choose have lower attenuation.
Its much easier to cool down the beer bottle down to the 35F. Better to strap the temperature probe to the side of the keg full of beer; and put insulated foam or something on the exposed side (so it doesn't read ambient temp of the kegerator)
You don't need a boil to isomerize the hops. That happens anything north of 180F. There are other systems that don't boil the wort. I think the pico brew. It's okay. It's not necessary. Are you getting a good hop break? the formation of foam and proteins on the surface? You want that. If not...
This has maybe been explained before, but I stopped washing yeast. Because there are all types of issues with trub, and hops transferring from batch to batch. So I then started overbuilding my starters. Read up on the process on brulosophy.com. Much simpler.
The longer time it takes for your immersion chiller to cool the wort, the more bitterness will come out of the whirlpool hops.
The temp issue may also extract more tannins / or even denature the enzymes to convert the mash.
Also what are you doing for water treatment? Do you know your mash...
This is how I do it: Primary ferment at temp of the yeast recommendation. After about 6 days test for FG. If it is what I expect then good. If not keep letting it ferment. Maybe raise the temp to get it to finish. IF I am concerned about diacetyl then raise the temp to 70-72 for two days. Cold...
I would say leave it alone. It was stressed from moving and putting it in the ground. It needs this year to just get the rhizome larger and store up for next season where it will really take off.
Tartness is probably some other off flavor. Could be the PH of the sparge (Releasing tannins); could be the temperature of the sparge. Could be chloramines / chlorine in the water; do you use campden tablets to treat the water; or adjust the water to get it in a nice PH range 5.6-5.2?
I use a champagne bottle half filled with santizer; I put my blow off tube into that; and I don't have to worry it will dry up; or where the blow off krausen goes; it ends up in the bottle.