As far as swimwear is concerned, I suggest wearing a bathing suit that comes with a skirt or wear a pair of shorts over it. Whether or not you wear a shirt is your own decision. I think you should keep in mind whether or not you'll be doing any actual swimming. If you're out in the ocean, you're going to want something that won't hamper you too much or you may get into trouble.
I don't think I can weigh in on the discussion about whether or not to go to a public beach, as I haven't been to one (during swim season) after my conversion to the Faith and haven't given much thought as to whether or not it's an occasion of sin. I'll definitely think and pray about it now.
As far as skirt length is concerned: if you can sit in it easily without being immodest, then it's long enough. Just because it's a little over the knee when you stand doesn't mean it's easy to sit in. When I'm trying on a new skirt, I always like to sit in the bench in the dressing room to give it a test.
I think a lot of good advice about the job situation has been given, so I won't comment on that.