distance runner interested in a tri

Hello to all,

I am a 29 year old medical student on the east coast, and have recently become interested in triathlons. I have been running for many years and am currently training for my second full marathon. I love running, but I want to try something new in addition, since most of my cross-training sessions consist of the elliptical machine... boring! I also want to get a more comprehensive workout and want to avoid inviting injury. 

One of my main motivators other than just changing it up is that I LOVE the ocean, but I'm kind of an uncoordinated swimmer. I love splashing around and definitely can keep myself afloat, but every time I decide to actually try to swim, I get knocked a** over tea kettle by the waves and end up back on the beach with varying degrees of wardrobe malfunctions  I took swimming lessons as a kid, but I'm very unsure about how to swim for a workout. Whenever I've tried, I end up a) feeling like I've gone allll this way, then turning to find I'm only a few feet from my starting point, and b) in the end, not feeling like I got a very rigorous workout. I think I mainly need tips on form and efficiency.

Also, I took a very bad spill off of my bike when I was little and have been a little tippy on a bike ever since. I think this can be overcome by just getting brave and accepting a few bumps and bruises as part of the journey. Although I would like some tips about what type of bike to look for. If it helps, I'm an average height, but fairly thin, female, and I tend to oversupinate when I run. 

Thanks all! Looking forward to beginning the crossover!