Hopefully you have a real contract that stipulates how the job should be done and have a "broom clean" provision, etc.
Hopefully you haven't paid them 100% of the price yet. Typically a significant payment is held until everything is done.
If the drywall comes to within an inch or inch and a half from the floor it might not be a big deal, especially if they are supposed to put baseboard over the crack.
If you don't have a building permit you aren't doing things the smart (legal) way. Where I live, they fine you and sometimes make you dig to inspect foundation footings, remove drywall to inspect wires and framing and insulation, etc. etc. I know someone who had to tear out the whole foundation of an entire new house b/c he didn't have a permit and hadn't had the footings inspected and they wee no good.
You undoubtedly have insulation building codes in your state that you are probably in violation of. Your roof might not be up to the task of supporting your region's "snow load" and may have to be replaced if sub-standard.
I would make a complete list of what you expect, including cleaning the site, fixing electrical and putting in ALL insulation, etc. etc. and go to a lawyer. For $50 or $100 you should be able to get one to write a decent letter saying that you will sue them if they don't finish the entire list within _____ weeks and include the date. You could probably mention that you will sue for fraud which usually incluedes triple damages. Send this letter registered mail return receipt requested. You should probably also put in the letter that failure to complete the list will lead you to file a complaint to the Michigan Bureau of Commercial Services, which is responsible for these things. See: http://www.cis.state.mi.us/bcs/
I have moved mountains with simple legal letters before. Don't be too greedy, just ask for what you have coming. The lawyer may charge you more b/c he may want to review the contract, etc. I have had lawyers not charge me anything for a letter b/c they wanted my future business, etc.