The most common difference in a Trap gun vs a Field gun is that Trap gun is made so the shooter purposely shoots 'high'. That's done by the stock comb being high by design placing your line of sight above the guns rib.
You see the bead at the end of the bbl AND you see plenty of bbl rib.
You are pointing the gun high and it shoots and hits high.

Thats a built in function to more easily hit the Trap target which is always rising as it is going away.

Some shooters like more,,or less of that to be built into their particular gun. Along with Length of Pull (LOP), cast off (or cast on) on the stock, and a few other measurements that shooters can call on to make changes to up their score.

Trap shooters gun stocks are much like Bullseye shooters pistol grips.
Altered, spliced in, rasped down, taped up, lengthened, shortened, canted, all sorts of adj trying to find that just right fit.

You don't absolutely need any of these. Just a well fitting stock that doesn't beat you up when you shoot plus it doesn't require you to assume a yoga position to cheek the gun and sight the target.

Learning the different leads and basic shotgun wing shooting techniques go a long way to success.
1oz loads in a 12ga will do just fine. Even the 7/8 oz in #8.
Full chokes print a dense pattern out there and unless you are going to buy tickets and ride those targets till they nearly hit the ground before taking a shot, the lighter loads will do. They are much easier on the shoulder.

I wouldn't recommend a specialized 'Trap' gun to start out with. If you have or have access to most any well made repeater in Full or Mod choke, take it out and give it a try.
You'll soon know if the sport is what you think it is. Or maybe it's not and something else may be a better fit like Sporting Clays or Skeet.