Racing Starts at USMS Meets.

Hi, I am somewhat new to Masters Swimming. I swam competitively ( somewhat!) when I was younger but for the last 30 years have been a fitness lap swimmer ( 1650yds @ 24: 30 ) I have done a few postal challenges and have been thinking about competing in a meet, it has been 30 years since I have started off a block or dove at all because I have a bad shoulder. Long story already but do they allow in water starts? Is this to geeky to even show up at a meet? Do I just have to figure out how to dive without dislocating my shoulder? I train alone so don't have access to blocks. Any help would be GREAT! I have really been enjoying my swimming and trying to get faster, fun after 30 years of just fitness swimming. Thanks, Paul