What would be the punishment for 70 canniabis plants?
Would it be cultivation an supply or both?

Would it be a custodial sentence?
If I wasent preasent at the time the police visited would they have to leave evidence that they have been an can they leave my house open to the public/

No they don't have to leave notice they were there, And yes it may be left open.

Yes it is normally a prison sentence,