Airforce Zeroing Airforce Texan SS CF .457

Hey all...Newbie here to the airgun world. I have done plenty of lurking here and a lot of good info. I just had a couple of questions for you all. I picked up an Airforce Texan SS CF .457, mounted a Vortex Diamondback 3-9x40mm and will be shooting NSA 350gr HP and 240gr HP (based solely off information from the website).

Yong Heng 4500psi compressor
2 6.8L SCBA tanks
Caldwell Chrono

I shot a few times already just to test 'er out...shooting resting on a fence post at about 40 yards. Got it relatively close. Now for the real sight in...

1. The temperature has dropped this week to about 10 degrees. I was hunting last week and it was in the 30s and 40s. Should temp fluctuation be a concern for accuracy? Say I sight in a when it's 10 degrees and hunt when it's 50, would there be any wild fluctuations?

2. What distance would you recommend a zero. I was hoping to do 75-100 yards. I am hoping to take whitetail with it inside of 100 yards. So maybe start out at 50?

3. I have done preliminary research on the power wheel settings and I know they will probably be different for the different weight of slugs. I was thinking of hunting with the 350gr, will the POI be wildly different between the two weight slugs? Has anyone been able to have their gun zeroed for various weight slugs by changing the power wheel?

Thank you all, I'm sure I'll come up with more as I go down the rabbit hole...already looking at adding Huben K1 and GK1 but wanted to get the hunting gun ready to go first.