Oh no, you will get swum over at the start. My first tri, someone nearly took my timing chip off. The best strategy, especially since you said swim is a weakness for you is to start at the back and to the outside edge of the wave. Let the fast people go. Move back into the main line once things have spread out and a rhythm has been established.
GET A SUIT...they are awesome. Depending on how much boobage you have you still may need more support. Mine doesnt have a shelf bra because for me shelf bras are useless.
I get one of these bras in black:
http://www.championcatalog.com/cgi-b...y?prnbr=CH1018
and wear it UNDER the tri-suit. It is made of a similar material to swimsuits and will dry quickly and still have complete support for the run (I was a 34DD last triathlon...I know support! - these are my standard running bras, but they are great for tri's) - if you need real support I suggest getting your real band size (professionally measured) and one cup size smaller.