You may notice that all the support references send you here first. They know the other users that volunteer here know the answers, assuming the question is posed properly. They also know we cost nothing. 

In short trust them and come here first. I admit that I know more than many of the Reps. I am a 40 year user, but like  you I don't know everything yet. 

I would agree with the reps about withholding on the IRA. That is 2020 withholding, regardless of whether the $100K is taxed now, or over the next whatever years. Just like a rollover - Unless the withholding is replaced the full $X is reported and only $X - withholding has been rolled over, yielding a taxable IRA equal to the withholding. 

I think you have to admire their ability to admit ignorance. 

Hopefully you are finding the latest update does know about the UI limitations.