Distance Runner trying to get into the Swimming Groove

Hey there, I'm a distance runner and want to start swimming - the way it's meant to be done. Right now, I am ridiculously slow at the freestyle and backstroke. When I feel like I'm moving at a reasonable speed I look to the lane next to me and see a guy moving effortlessly, just gliding through the water, 3x as fast as me. I don't know why I move so slowly. I've watched videos and it just seems like I get none of that fluid propulsion forward. I also get out of breath extremely quickly, it seems. I run a 5K in 16:18 and it's a struggle completing 100 yards in the pool. Lastly - I can not make sense of this - it seems that my breathing is just fine until I make that first turn - and then, counterintuitively, after I take that breath and flip around I feel like I'm out of breath, and the rest of the way is a struggle. I don't know how to breaststroke or butterfly at all. I suppose I'll leave that for later... Suggestions?? Thoughts??