I have lots of experience and would be happy to help in any way that I can.

I would go with the tri shorts and get a tri top. The tri gear should not slip or slide if you are swimming without a wet suit. You want to fiddle as little as possible in transition.
Some of my tri tops I wear a sports bra under also. Just a little extra coverage. In the warmer weather, I am sweaty as soon as I start to ride anyway, so it does not matter if the sports bra is wet.

What else???

Are you going to run in socks? Is there a run to T1 from the swim exit?