It is entirely possible. Totally up the police officer who drove you home. If he/she simply drove you home and said nothing more about it, then I would guess you are safe. Usually, if the officer was planning to turn you in, he/she would have inquired about what you had been doing that evening to see if you would admit to drinking.
When looking for a lawyer, you should speak to several, meet personally with a few and then make a decision based on experience, knowledge, price and your gut reaction. I would start with a search on the AVVO site for lawyers in your area.
I would speak to an attorney right away. There are potential drivers' license consequences that will automatically take effect, even before you would receive the paperwork from the court. Time is of the essence here as you only have a limited amount of time to take appropriate action.
It depends on what he is suspended for, but the police can impound his vehicle on the spot and he will have to pay to get it out. Depending on the reason for his suspension, he could be subject to arrest. He will need to speak privately with a lawyer to figure out his situation.
A good DUI lawyer should be able to work out a deal that is acceptable to you. Your bac numbers are all over the place and could be a good starting place to challenge your case. Also, there is a good case law right now challenging DUIs. Contact a qualified lawyer now to figure out your options.
Actually, both states could. Minnesota will revoke a person's driving privilege for any offense that occurs within the state of Minnesota and also may do so for violations that occur outside the state. Wisconsin may also impose its own penalties because the driver was licensed in Wisconsin. Get a good DUI lawyer right away to make sure you don't miss any deadlines.
Unfortunately, there is no simple answer. There will be both advantages and disadvantages to pleading to either charge. You will need to speak privately with a criminal defense attorney to learn about your best options.