1. contact some schools you are interested in and clear up the obscurity about the english credits. you could be fine and potentially save yourself the trouble of taking another class.
2. you said UCI accepts CC credit, so i'm not sure what you're asking about the stats class...
3. if you end up taking these classes and applying during the summer, yes, you will be moderately busy. there's not much else you can do about that; just do what you can on the side.
4. if your application is lacking (needs "bolstering") then you should address these issues. what will you be doing abroad for a year? is this the best way to spend your year? maybe wait another year before applying (i don't know, so maybe???)
5. if you want to do something else "productive" during the summer, you can always hold off on pre-reqs until the summer before you matriculate. i don't know you, so i can't offer any specific advice, but like you said, aim for either something medically related, something service-oriented, something you are truly passionate about (non-medical), or ideally something that encompasses all of that.
i guess i didn't really answer any of your questions, but i do hope some of that is helpful.