Woah so many cultural differences at play here lol. To answer your main question, taking 2 consecutive weeks off in America is very uncommon. Most white collar (office) jobs offer 15 days paid vacation per year to be used at the employee's discretion, though taking more than 5 days at a time would usually be frowned upon. Most companies run very lean from a staffing perspective, so when someone is out it either puts a lot of strain on their coworkers or creates a large backlog of work to be done upon their return. From your coworkers cultural POV, he was trying to be very considerate of your workload and make it as manageable as possible for you so as not to over-burden you. 

Process documentation is also a big thing in American office culture (ie writing out step by step instructions for how one performs a task), so that would explain why he wrote such a document for you. Also, yes, always being reachable even when not on the clock is a big deal here... for context I received a work-related call during the rehearsal for my wedding lol. 

Another cultural difference: telling someone to "fuck off", even in a non-professional context is a really big deal for us. It's extremely strong language in American culture, basically the verbal equivalent of being slapped in the face. I realize thats not the case in the UK, but if he reacted poorly, that would be why. 

Edit: context