I too am a big proponent of full face helmets. In a past job, I've seen the aftermath of the accidents that "nobody thought would happen". The more protection - full face, all leather, etc. - the better. Full face helmets take some getting used to, but they are well worth it.
Re: the hair - I have slightly longer than shoulder length hair. On my motorbike commute to work, I leave my hair down; as I rarely go past 55 mph and that's only for about 5 minutes. However, on longer, faster rides, I have learned (the hard way!) to make sure it is well tied back in either braids or a ponytail. (Either are fine with the full helmet). If it isn't tied back, it gets ridiculously tangled! Also, one other hint - best to avoid hairspray anytime before the helmet goes on...or helmet head is guaranteed! Other, light, leave-in products (spray varnish/biosilk) are OK though.