Plague level for mod

[StarBaseSweeper]

About modding Plague weapons:

When designing a prevent plague facility or component, any number seems to be used for the plague level.

However, when designing weapon, only level 1 to 5 are ok.

So 2 questions:
1] Is it possible to design weapon with plague level > 5 ?
2] What is the use of the damage of such a weapon (let's say I put for damage/range 200 200 200 0 0 0 0 ...)

Thanks in advance