Adverse possession cannot be used to take government land. Even if you could, by asking if you could buy the lot, you would likely fail to prevail on the use of the land that is hostile to others and open and notorious to the true owner.
In most cases, verbal contracts are every bit as enforceable as a written contract (just harder to prove) but this is not the case for your fact pattern. The statute of frauds requires that any contract dealing with an interest in real estate be in writing. There are exceptions, like an admission by the party or a written confirmation.
Contact the Minnesota Department of Revenue to be certain but, since you are operating a service primarily, you should not have to collect sales taxes. If you sell products into your clients, you will have to collect sales tax. If you are looking for a business start up attorney, feel free to give me a call.
Images of others can be used if you secure a license from them. All images have copyright protection. You need to obtain permission from the creator and/or owner of the image. There are exceptions to the protection under the fair use doctrine, if your use was to criticize, comment, news report, teach and some other things. For commercial use though, you will have to secure a license most likely.