My understanding is that in California, a root structure is considered a complete plant. In the event that police are going to be counting your plants, they're counting individual root structures. If you have 50 non-rooted cuttings in a tray, that's 0 plants, but if they're all rooting, that's 50 plants.
Also, I've been told that males don't count at all.
The way I understand 215, if a jurisdiction doesn't want dispensaries in their town, they
have to draft ban legislation or they can do nothing to prevent dispensaries from moving in. The numbers I've seen indicate that upwards of 140 of California's jurisdictions have enacted such measures.
It's also fair to note--if 19 passes, the local jurisdictions clause works the opposite way--prop 19 dispensaries will be banned by default and local jurisdictions would have to draft legislation to create a licensing and legalization framework for that jurisdiction.
Regarding SB420--it is correct that the portions of SB420 that sought to cap patient plant/dried limits were found unconstitutional in People v. Kelly and subsequently revoked. Currently, the only limit is your doctor's recommendation. Previously, the statewide limit was 8 ounces of dried and 6 mature or 12 immature plants, again, whatever that actually means. Local jurisdictions had the power to raise those limits as many did--for example Oakland changed it to 3lbs of dried and 32ft. of canopy space.
link:
http://www.ballotpedia.org/wiki/index.php/People_v._Kelly