Nemesis buffs for 2v8

I've some simple buff suggestions for the Nemesis that you might like:

1. There are 4 Zombies on the map by default instead of 2 Zombies.
2. Zombies have their default movement speed increased by 40%. (1m/s to 1.4m/s)
3. Contamination buffs Zombie's movement speed by 10%. Stacks per survivor contaminated. (+0.10m/s per contaminated survivor for a maximum of +0.80m/s when all survivors are contaminated.)
4. When all the survivors are contaminated, increases the Zombie's movement speed to 400% for 60 seconds. (Zombies will have 4m/s for 60 seconds when all the survivors are contaminated (Does not stack with default movement speed and contamination bonus movement speed))
5. A survivor who is both contaminated and have the Uroboros Virus fasten the passive Uroboros Infection Meter to 2.0c/s.
6. Every 2nd Generator completed adds a Zombie to the Trial.

What do you think of these buffs? Would it be too strong, decent or still too weak? I wanted to give him a buff which spawn a zombie for every survivor killed but I believe that would only incentivize tunneling one survivor out so instead of killing survivors to spawn additional zombies, a zombie spawns for every 2 generators repaired.