I haven’t configured multi-wan yet, however i want to know something, because the documentation till now is showing just 1 multi-wan connection or i have just missed something completely. This is how my situation going to be.

I will be having 4 WAN-connections. I want 2 wan connections to be “multi-wan1” and the other 2 to be “multi-wan2”.

“multi-wan1” i am ONLY be using for downloads (torrents, newsgroups etc.). While “multi-wan2” i will only be using for internet/youtube and such.

Now is my question is this possible for example using vlan or something like that?

Yes, you should configure switch vlans and interface for each wan connection. Then with mwan3 package you can configure the routing for different services/target ips/ports etc.