First, IANAL. I took some law classes in college, but still. Bert P. Krages, Attorney at Law is however, and he has a post on his website regarding this. He even created a downloadable PDF regarding photography laws.
Basically, unless there is a clearly posted sign saying it's illegal to photograph something, you can go right ahead. With photography, it matters more who took the photo than its contents. You can't just use a photo that Jim Smith took without permission, but you can photograph Jim Smith's house without his permission, without fear of repercussions. That doesn't mean you won't get harassed, however. Jim may just decide to come running out of his house with a gun screaming for you to get off of his property. That may or may not be legal for him to do, depending on the state, but that's the risk you take. The PDF I linked to has various tips regarding this.
As far as writing, as long as what you are writing is true, you're okay. If it isn't true, you can be sued for libel. For instance, say that Jim's Restaurant is filthy. You visit Jim's Restaurant, and notice the uncleanliness, so you write about it on your blog. Now, if Jim see's this, and doesn't like it, can he sue you? In short, no. In order to sue you successfully, he has to prove that when you visited, the restaurant was clean, that you willfully intended to damage his business by lying, and that he lost business because of it. Due to the difficulty of proving even one of those statements, it is extremely difficult to prove libel.
In short, you are probably safe. If you are really worried, there are courses of action to take. Firstly, you can hire a good lawyer, who can evaluate your work and give a recommendation one way or the other. That lets an actual legal expert have a detailed look at your work, and he can tell you exactly what is wrong, if anything. Secondly, and probably simpler, you can just make a simple disclosure form, and get the owner of the property to agree explicitly to allowing you to do your work. That gives you near 100% indemnity in court. It's also the friendlier way in my book. Most places would probably welcome the publicity, for that matter. :)