The 8201649 doesn't come with the metal piece to rebuild if the tab has broken off. I would just take the 8201756 with you as all the pieces you need are in it. And as BryanS says it makes it a lot easier fit if you shave the tips off. Just take your time and you'll be fine, good luck.
If the bake element checked out okay I would lean towards the control being the problem. Knowing these Frigidaire ovens its most likely a burnt solder joint at the bake relay on the board. Not sure how good you are at soldering, but if the burn isn't too bad you could try repairing it yourself. Barring that the control for your oven is no longer available so your only recourse would be to have it taken out and rebuilt.
Those DSI ovens are a little more complicated in how they work and how they are diagnosed and repaired than the glow-bar ignition ovens. If everything else has been changed and checked I would look towards either reversed polarity at the outlet or something going on with the wiring harness.. maybe something the first tech did on the first repair when the gas valve was changed. I've seen plenty of shorted/pinched wires going to the spark ignitor causing all sorts of weird temperature issues as the DSI module can't detect the flame.
They have replaced the 'duckbill' grommet (the 2nd extended one) with the W10619951 drain tube kit. It's a P trap drain tube kit... comes with a drain spacer and 2 P-traps for the 2 different applications.. you just choose your flavour. I've done a few of them... pretty easy. It's a case of what's old in new again.
If the freezer is at -10F then the fridge should be a lot lower than 50F. Make sure the fan is running in the freezer when it's running. If I was running this call I would check to see if there is ice build up in the freezer section at the back. A lot of times the drain backs up and causes the trough to overflow icing up the air passages preventing air from properly blowing into the fridge section. If you can take the back panel of the freezer off and check for ice buildup. There's nothing wrong with the sealed system if it's getting down to -10F. Possibly just an airflow problem.
If I was a guessing man it sounds as if the power shower tube is leaking. It goes from the main motor, along the left side of the tub to the top of the dishwasher where it supplies water to the top wash arm.