If you want to prep, buy a still and have plenty of reserves of beer, wine, and especially hard liquor. Make friends with all the local hardasses. There, now you can open a bar and as long as you give the local thugs free/cheap booze you're 100% safe since no one fucks with the place the local gangs hang out at but it sure will get lots of business since everyone wants drugs or "security". Making it into a full-on restaurant is even better.
At the end of the day, Detroit is still a functioning city. The gangs police whatever the Detroit Police aren't able to with brutal efficiency. People still get food and water and employment. You can send your kids to any public school in Detroit and theoretically (key word) they will learn everything they need to.
Detroit's many abandoned buildings create a lot of opportunity though. In addition to free housing (which denies the government and landlords of revenue which theoretically would be reinvested in the city and make Detroit a nicer place), they provide good places for crackdens and as you pointed out, are loaded with copper and other shit you can strip out and sell. There's also legal shit that goes on like how some of those buildings and the land they once sat on are used for urban farming.
It's not hard to build a durable car running on ethanol or shit like wood gas. Hell, you can convert your own car to run on vegetable oil (aka grease). And remember, the first car was invented in the 18th century so cars aren't high tech.