DANGEROUS TERRAIN ERRATA

Can I take damage from Dangerous terrain multiple times during the same action, (by say moving off and onto it several times?)

No. Community Errata: Treat Dangerous in the rulebook as reading:

DANGEROUS: When a unit performs an Action while contacting this terrain piece, before resolving that Action, it suffers D3+1 Wounds. When a unit moves while contacting this terrain piece, it suffers D3+1 Wounds. When a unit suffers Wounds from this terrain piece, it can’t do so again until it completes an Action or stops moving (unless that movement was part of a charge action).