I haven't done this particular trip with Trek Travel but have done several others and would recommend them
https://trektravel.com/region/europe/scotland/

Bikes are included in the trip and even though they are "group" tours, you don't have to ride with other members of the group unless you want to.

If you've never ridden a traditional road bike before, maybe you could get a bike fit before you go. Let a professional help you through the process of determining your best fit coordinates. Take the info with you and the bike rental folks can help you set up the bike to those coordinates. If you start from scratch when you get there, the odds that the person setting up your bike will almost certainly not have the skills to do it well.

Yes
Depends on the rental. Probably? Bring shoes and pedals at least.
Depends on the group but ime bike tour groups are super laid back.

I did a couple vbt tours as a competitive cyclist over a decade ago. Overall had a blast. Come into it expecting a vacation and not a training experience and I think you’ll enjoy yourself. A good gps would have helped, because my cue sheets weren’t always great.

Definitely bring your own pedals and shoes. The Trek travel trip I did, they now have Garmin head units with all the routes on them. I had two or three routes every day to choose from (normal, short and longer). So no worry on the cue sheets anymore.

My wife and I are up to trek travel trip nine in April.

Some times we bring tribikes some times not. I'd say bringinoa tribike depends.. A) what type of bike does the tour company have. If trek they are nice madones but others may be heavier steel frames.

Do you want to ride with the group? In aero, you'll probably further ahead (and less wanting to hang out near everyone else). You'll also likely find yourself sitting up out of aero at beginning and end of days periodically.

We tend to bring bikes when we are explicitly training for something,.. And leave them at home when we just want to go ride. It's kind of nice when they take care of everything(when it's your bike they can't)