Legalization:

Legal home growing for personal use without the need for a license - I would say 15 plants or fewer (this is a generous limit to allow for a few varieties of mother plants, small scale hobby breeding, etc.)

Licensed growing for sale - This would be similar to the licensing requirements for micro-breweries. This should require annual/bi-annual license renewal. These grow operations would be subject to health and safety inspections to avoid such dangers as mold, unsafe fungicides/insecticides used during bloom, and etc.

Legal sale at licensed stores with a system similar to current liquor licenses. Any coffee house, grocery store, liquor store, etc. should be able to apply for a license and sell Marijuana over the counter to adults. These licenses should be granted by the municipality just as current liquor licenses are.

As far as weight limits, why? Is there currently a limit on how much alcohol you can possess in your home? As long as anyone can purchase over the counter from local retailers then we don't need to worry about how much is personal use and how much is intent to distribute. I've never heard of anyone being busted for having too much Budweiser in their home without a license.