First Tri, bouyancy shorts?

To my knowledge buoyancy shorts aren't "legal" in races where wetsuits aren't allowed (if water temperature is too high). Sometimes beginners are allowed to wear wetsuits or buoyancy shorts anyway, but will not be considered in contention for age group awards, qualifying for other races, etc., if they do. Those probably aren't issues for most beginners anyway. Honestly I don't know how this policy is enforced--I've always followed the race director's decision on wetsuits as I am usually in contention for AG awards. Maybe the "illegal" wetsuit people start in a separate beginner wave, or they check swim exit pictures or something. There are also exceptions that make wetsuits legal in higher water temps for a few categories of athletes like the very old, or physically challenged, in some races.

At any rate, I would work on improving your swim skills until you don't feel the need for extra buoyancy (and not using the shorts as a crutch in training); if water temperatures allow it, buy or rent a wetsuit and wear it instead.

Depends on the water temp.
If it's wetsuit legal, you can use the shorts.
If not, no shorts.

But, also consider a speed suit. Legal for non-wetsuit because they are not rubber, but compresses your body to reduce circumference to aid swimming speed.

Definitely learn to swim without aids if you are going into the warmer months with the race.