I don't know about generalisations.... my nephew just turned 17 - and you would SWEAR that him and his group of 'best' friends were all lovers. They are nothing like guys were like back when *I* was in high school (granted - that WAS 30 years ago ;P) Now, it could be the way they were raised I guess - but they have no trouble showing affection, or with physical closeness.
As for compliments - it's an easy answer for me as a gay man, and while I won't just walk up to random strangers telling them they're hot, if it's someone I know at least reasonably well - I'll let them know (even moreso if there are others around - especially a girlfriend I know - nothing more fun than trying to make a straight guy blush )