Firstly, in my experience of going - ive seen zero incidents (wasn't there last night) aside some Hammers fans arguing with stewards, i sit on the east stand.
The issue between the fans seems now to have died down, it was mainly down to having persistent standing at the Bobby Moore Lower at Upton Park - as a club they turned a blind eye to that part but at the new stadium it's simply not allowed - so you have fans that have always been standing coming to a new stadium and being told they must sit - it caused some anger with certain fans.
the very small minority looking for trouble, i'd say look like ex 80's types, complete di*kheads - yeh you get some teenage wannabe Danny Dyers. But honestly you are talking less than 100 people out of 57,000 - thats all it takes for the Media to latch on and make it all sound 100x worse.
The segregation is no different to how it was at Upton Park - Just with a whole new stadium and with some relatively small incidences blown out of proportion there was always going to be trouble last night. It will all die down soon.