I think 5 was overrated so I can't offer any insight.
So why did I post you say? Well.. no reasons. The skill system is used to upgrade weapon firepower etc. No clip size. You pick up skill points that enemies drop and spend them in a shop and place the skills on your character.
There are several skills, firepower, melee power, item drops, rate of ammo drops, amount of ammo that drops on pickup, grenade power, break out of grapples etc etc.
Co Op is great if you enjoyed RE:5 Co Op. --- Use an authenticator. No excuses. You get hacked, your fault. Authenticator. Get it. Use it. Love it. Massage it. Feel it. hold it. Type it. Use it. insert it.