(Migrating from TimeCapsule and Choosing a New User for my New MBPro) 2 QUESTIONS

I have a 2012 MBPro it has 10years of info on it which totals 680GB stored on it, most of it being documents and photos. I dumped of 40GB of old documents i dont need anymore, down to 640GB it is all backed up to my 5th Gen TimeCapsule, My oldest back up is 3/25/2018.

I also had 2 users both were administrators, 1 original and a second after my hard drive was changed and i migrated a backup from my TC. i choose change the rename option not realizing that would keep the old user & home folder and create a new home folder and user. so i thought when i migrated to my new 2021 MBPro i was going end up with a third user. So i got this idea ill delete 1 user/admin before the migration, not knowing i could choose to replace the account and the old home folders would be deleted. That being said

i asked in an apple forum could i delete 1 of the users because i did not want them on the new MBPro, i was told yes i could as long as they were both Administrators. I was also given the same advice here in apple communities after the fact. This is not true, upon deleting 1 of the Administrators i lost access to some of my TimeCapsule, I could go into Time Capsule see all my backups back to 3/25/2018, but i could only select backups after date i deleted 1 of the 2 Administrators, which caused my to lose access to 4 years of TC backups.

I have a new 2021 MBPro M1 Max that i will be setting up, I am going to use Migration Assistant and i will be choosing a new user and delete the old user as shown in the image below underlined in green.

Questions:

1) when i migrate from my TC choosing the option underlined in green, will this NEW USER be the new Administrator & have access & control of everything Migrated over to the new MBPro?

2) is this migration going to migrate over all the backups on my TC all the way back to 3/25/2018 giving me (the New Administrator) my access back in time machine to all of backups i can currently see in time machine but can not access?

on my 2012 MBPro when i go into TimeMachine after the day i deleted 1 of the 2 Administrators i can access everything except some emails are blank, so i got out of TimeMachine and into my email, those same emails are are blank, i figuring this is due to encryption and the deletion of that 1 Administrator.

there is one particular email i would like to retrieve that was accidentally deleted 3 weeks ago. im hoping after migration to the new 2021MBpro i will be able to enter time machine as the new and only administrator go to the day before i deleted the email and restore it.

thank you all.