I bought an iPhone 6s Plus from Apple a couple of years ago. Can I enroll in the iPhone Upgrade Program and upgrade it to an iPhone 8/X?

I am doing in-store pickup but I want to take it back home with me to do the transfer and make sure all my 2FA (two-factor authentication) apps are properly transferred over, etc before I return the old (current) phone back in-store to complete the iPhone upgrade. When we do the mail-in kit, it says we have 14 days, so there is a period where we would have both phones are home, but just wondering if this is possible with in-store pickup also. Do I need to replace the iPhone at the store at pickup to walk away with the new one for the iPhone upgrade program?

I wonder if I should participate in the iPhone Upgrade Program - specifically based on how does ann annual upgrade affect the average age of accounts on the holder’s credit report. Specifically, does each annual upgrade count as a new account, and thus your AAOA goes down or is it just like a credit card where it has a "new limit and balance" next month?

I have downloaded a software linguist. This software is able to translate the in writing. Can Siri be linked to this software to read and write Tamil?

Is it possible to do the iPhone upgrade program without having to either upgrade an existing line or adding a new one? Just doing it for monthly payments?

I'm really not sure whether this is really on-topic, but here goes... How does the iPhone Upgrade Program work? I understand the information on the Apple site - I pay them monthly, no interest, with a small upfront payment & after a year I can get a new phone. My contract, however, runs for 20 months. Right. So, I'm paying say 50 bucks/quid/shekels for 20 months, yet I get a new phone after 12 months. Where does that leave me? 1. I continue to pay off my existing contract, another 8 months at 50 'currencies'? ...and I also have to start paying for my new phone, so I'm now stumping up 100 'currencies' per month to have the new one & an old one I no longer need? Or... 2. they take back the old phone & let me off the last 8 months & I just pay a new deal of 50 'currencies' for the new one, with a 20-month contract unless I repeat the same after another year? or is there a 3. ?