Need some help understanding Persistent Plasma and The Mole

I recently got these two overclocks and checked the wiki since it's usually pretty thorough, but it didn't have the answers to my questions, so I figured I'll try asking here.

The Mole is the one I'm most excited about. It says on the wiki that the damage bonus is affected by the charge level so I was wondering if the overcharger upgrade increases the damage bonus or not. Or maybe the 150 kinetic damage cap is reached with the overcharger upgrade?

Regarding Persistent Plasma, I wanted to know if any of the EPC's upgrades affect the lingering damage zone. Like increasing the area of effect or the DoT's DPS. And I was wondering whether or not you can stack multiple plasma DoTs.