I took a parenting class recently taught by an LDS counselor and I think a lot of it applies to marriage too. She said that most of the time, anger is the result of unmet expectations. She pointed out how often when we get mad at our kids, it's because we feel like it is a reflection on us. Your wife getting bent out of shape about the home teachers coming over to a messy house is probably due to the fact that she doesn't want to be judged, because people typically expect the woman to be the housekeeper, so she thinks they won't blame you, they will blame her. Unfortunately, I don't know how to help her get over that, but I sure wish I could.

Or maybe she has different clean standards than you do? I have relatives who are borderline OCD and you feel like you can do no right when it comes to cleaning/organizing and I have tried to explain how we don't all think the same way or are bothered by the same things, plus we're not mind readers. Also, my friend went to a marriage seminar and she was taught that you always have to ask and not assume your spouse is just automatically going to do something. They said, "If they say no, that's when you get mad." She grew up in a family where people would see a need and take care of it. His family is the opposite - you have to ask. I have a lot of friends who get all huffy because their husbands didn't instinctively know that they wanted them to do x, y, and z. My husband is great about helping when I ask him, but no matter how disgusting the toilet gets, he never takes the initiative and cleans it. He does do the dishes without being asked, so I think he just has different cleaning priorities and I can't expect him to think like me.
As far as your wife wanting things resolved before bed - Is she not able to sleep unless you guys have made-up? I think the don't go to bed angry thing is terrible advice because you might have a better perspective after some rest, but some people can't rest until everything is OK.
Also, there is sometimes a big issue and people will focus on all the little things too, thinking it's part of the bigger issue. I don't know if that's going on in your marriage or not. Anyway, prayers for you and your wife.