Can Men And Women Friends Have Casual Sex Without Making The Friendship Weird And Or Destroying It All Together?

You will find that some woman are totale fine with it.  Normally the woman that will be fine with it are your business woman because they don't have time for serious relationships and therefore are quite happy to have friends with benefits as you put it, not that Im saying that all business woman feels the same way, but mostly I agree with Nassy.  We think with our harts and not our minds and that makes us emotional, not that I like to admit it.

Women are too emotional about sex, so honestly I don't think it is possible for "most" women...♥Nassy

Well you'll have to pick the right people. You know and we all know there are men and women out there who prefers friends with benefits. Then you can also consider what Nassy and Tamy mentioned. There are many different people and when you give such a intimate no-string attached relationship, some people will do intend to just fall in love the way you treat them during intemacy.
Get the show 'Girlfriends', you know that guy Will who's always there with the girls? He had his own friend with benefits and they end up loving each other with denial.

My guy friend and I had casual sex and kept a friendship without having a serious relationship, it depends on what you  two are after cuz it can start as a fling and wind up being more.