a british or english bag
'Steam' is 'stoom' in Dutch. If you mean the verb it is 'stomen' in Dutch.
A dutch man is a man from the Netherlands, or as we dutch say a dutch man is a "hollander"
'Weed' is 'onkruid' in Dutch. If you mean the verb it is 'onkruid wieden' in Dutch.
It is a wrong way of saying douche bag.
Back of the net (you mean as in football?): "In het net" is the best Dutch translation for it.
This is old Sixties slang. You don't say it as "your bag" - you say "NOT your bag" as in not the sort of thing you care for. If someone offers you some drugs (as people often did in the Sixties), you could say, "Sorry man, it's not my bag."
'Can I have it?' is in Dutch 'kan ik het hebben?' If you mean 'may I have it?' it would be 'mag ik het hebben?'
If you mean to say that something is really awesome (cool), than in Dutch you can use the same word. If you mean to say that something is cold (cool), you can say: koel or koudor fris.
'mail' is in Dutch 'post' I think that you mean mail in letters and that sort of stuff. Because an e-mail is also e-mail in Dutch but they also say 'mail' when they mean e-mail.
You have to translate it. Or do you mean something specific?
If you mean and a like "A dog and a cat", it's "en een".
The word "Dutch" in Dutch is "Nederlands."