Mate,
Try the goggs out for fit and comfort, thn buy what suits you, I find the proto EL's comfortable, but they have a single lens, that fogs up, the FS is almost the same fit, but better made, hence the difference in price (and with a thermal lens too, I think). A couple of our guys bought cheap basebal (thick material) caps (fron Asda I think) for a couple of quid, then sewed the pads from some bird's bra in to the gap and wear them backwards. If your gf/mum isn't willing don't nick you neigbors of the line, that behavior is still frowned upon I beleive
At the end of the day, you'll look like an escapee from deltaforce in a 'peanut', get what suits you, then pad out your dome if you think you need it!
You'll forget about headshots, once you've been shot in the side at close range in a mugging, I got shot a dozen times on a run thru last weekend (by over excited noobs whilst breaking open a training game) and didn't notice the headshot I took for a couple of days, compared to the others, the worst are neck shots, they look awful the next day (would recomend a neck gaurd to start with) but you need to get used to taking a punishing, if you want to play with the big boys, it's all part of the learning process. The only time I suffer now is from newbies who don't know when to stop shooting!