Rusty, tumble turns are fab for pool based Tri's, imagine the time you'll save per length!!! re bilateral breathing try single arm drills using a kick board. Rest one arm on the board and do the length front crawl using just the one arm,breathing to the one side only. this will help you get used to the required head position. You really need to master bilateral breathing for open water swims as the current could be a problem for you otherwise.