For everyone that's doing any models based on my concept designs above. The only weapon that is questionable is the alien blaster launcher which was inspired by and looks close to the original.
The laser weapons, plasma weapons and human (box shaped) blaster launcher are my designs and there isn't any problem with the copyright of those. I'd say that the blaster launcher should be dumped in favour of something a little more radical. I was thinking something like a backpack that sits on the operator's shoulders and has a cable to 'mind link' the operator to it.
Sort of a portable mortar on the back of the alien operator. When researched for human use, the closest we could get to it could be a similar arrangement but instead of a mind link the operator wears a (predator style) arm computer that is linked to a minimap for setting waypoints before firing.
I'd agree with Drewid on the base tech level weapons, definitely contemporary projectile weapons. The HK and the FN P90 would be perfect as the ranges the game is played at would suit those weapons perfectly. For anyone that doesn't know what an FN P90 looks like, here's a pic of one.