Losing my virginity, need advice...

DennisG2014 went on a bit of a rant said
7

Smartphone virginity, that is.

Sorry for the clickbait title, I couldn’t resist.

So, here’s the background - I’ve used a flip phone for aeons, never wanted a smartphone, figured I’d get one once the flip phone no longer functioned.
Well, last week I traded in my 11y/o car for a 2019 Toyota which came with an ‘Entune 3.0’ infotainment system that can do a lot of cool stuff, but none of them without pairing with a smartphone.
With no smartphone, it’ll do am/fm and came with a 3 month trial of SiriusXM - that’s it. No nav, no personal music collection or even CDs. For the 1st week I’ve used my stand alone Garmin GPS which, unlike in my Subaru, has no good place to sit on/in the console, and my old iPod Nano, which needs to be wired to the aux jack. With the GPS also plugged in to the power jack, it’s just a mess of wires and unsecured devices rattling around.

So, I went to Apple’s clearance site and scored an iPhone SE 32gb (gold, no rose) for $250.

Now, I need advice on choosing a plan.
The iPhone came w/ a T-Mobile sim card but is unlocked.
My flip phone uses Verizon Wireless (and my home internet/TV/phone is also Verizon).

I’m actually reluctant to give up my flip phone as my mobile - even as relatively small as the iPhone SE is, it’s still twice the size of the flip, and I can’t see carrying that around in a pocket.

(I think) I’d like the iPhone to just be the brain for my stupid Infotainment Suite. It can use phone apps via Bluetooth or via Apple CarPlay if I wire it in w/ a lightning to usb cable that I’d have to buy.
Either way, it’ll display the apps on the 8" touch screen with the touch functionality.

I’m wondering if I should put the iPhone on a data only plan or maybe get a 2-line plan to include both devices.

I also suspect that it won’t take long for me to be infected with the smartphone-zombie virus and abandon my flip phone, so I’ll probably be better off w/out a contract.

Anyway - all that said, here come the real questions:
How much data am I likely to need? I have absolutely no idea how much I’m likely to use.
Should I get an unlimited plan or a capped plan?
Who’s the best/cheapest carrier?
Should I use T-Mobile since I already have the sim, or Verizon since I already have service from them, or someone else entirely?

Thanks in advance for any advice, I suspect I’ll have more questions.