THC is likely stored in fat cells, however most THC is oxidized and metabolized into various inactive forms, which is mostly what is actually getting stored. The blood test only looks for THC itself and not these metabolites, which is supposed to discern that the person is actually under the influence of cannabis
if they test over the limit. However, the discussion is whether the limit is high enough, and whether this 'built-up' THC can over time cause a person to fail a test long after they have ceased using the drug
As far as the bill, it allows people over the age of 21 to possess and use up to an ounce of marijuana
at any given time, as well as a certain amount of oil and/or products infused with marijuana. It also allows for the possession and use of paraphernalia, such as bongs, pipes, etc, as long as they are strictly related to the use of marijuana. Literally, recreational use of the drug is legalized, as long as one is not (under the law as written) intoxicated on the drug while driving, and meets all the rules
set out by the law. Sale of the drug by anyone other than a storefront licensed by the liquor control board is still illegal and prosecutable.
The full text of the bill is available online. I'm too lazy to look for it right now