1) Not really- one wife per husband, first come first served
Though it is true that some people have the urge to have many relationships, some only wish to have one partner- I think thats true of many animal species, so humans are no different ( you get gay animals too btw ). Most western cultures say its the law to only have on partner, I cant imagine trying to keep several nagging wives happy at once, would cost a fortune...
2) Not neccessarily, depends what their reasoning is ( 'burn the homos cos they am evil' isnt a good reason to not support same-sex relationships ). Some good points have been bought forward in this thread, but also some fairly weak ones too. Unless you could conclusively prove that same-sex parents leave their children screwed up in the long term its fairly invlaid to say they definatley would or wouldnt- makes me wonder if Hitler's parents were nice people or not, never seen any documentaries on the subject... ( IE nature vs nurture ).
3) Different cultures & communities have different view points on issues, but you have to take an objective view and decide if something ( like homo-sex ) is harmful to society or not really- think of all the great hairdressers & fashion designers we'd lose if homo-sex was illegal. One shouldnt force their views on other people, rather we should all respect eachothers views so long as they are well founded ( preferably with facts or research & well informed opinions, not just ' the bible says...' ).