As per usual, original letters are here.
LW#1: It's kind of hard to know what to say here since two couples, one vacation rental, two weeks kind of sounds like a Bob and Alice and Ted and Joan (or whatever that movie or book or whatever was titled) situation.
On one hand, you guys all totally get along and like each other, but the limits of that like were tested. Most people end up sick and tired of the other couple's habits. But apparently you guys got along so great that unexpected sex occurred, driving the limits in the opposite of their usual direction (ie towards too much intimacy).
I've been trying to think what I'd do if I were in your shoes, and the answer is this: Let the friendship fade. If you truly and honestly believe that this was a one-off on both their parts, then you know that the closeness between your family and theirs can get a little crazy.
I also think you need to work on your boundaries as a person, your husband's boundaries as a person, and your boundaries as a couple. There are appropriate intimate relationships, and there are icky ones, and this friendship got all icky all fast, and obviously both you guys and they have something going on that trips all y'all's triggers in inappropriate ways.
LW#2: The solution is to take her out to eat more or start cooking yourself. "I am a partner in a large law firm" says to me that maybe you can even HIRE someone to do the cooking for you!
Also consider getting yourself tested for allergies. And having your wife's iron gut tested for what it can do for military sciences.
LW#3: It is time for your yard to become just your yard again.
Sure, the death of a young man is a pretty big event for your yard to have been the scene of. But your yard is also where kids play, dogs scratch dirt and newpaper delivery boys (who are woefully undertipped) leave your papers by accident on occasion.
So go ahead and reclaim your yard. Take the stuff that has accumulated to his family's, and say that you want them to have these memorial items. His memory is now for them to maintain, you can't bear the burden of it being in your yard anymore. Make it clear that you are trying to be as respectful as possible of the things that have accumulated, of their sensitivity. Because they are probably extremely ceremonial people, try to collect the things in as ceremonial a way possible, perhaps going so far as to rearrange everything on a pallet. I am dead serious.
You may want to throw in something (true or not) that their son's death was a wrenching experience for you, and it is hard to see these memorials up day in and out.
BTW, if you find a drunk, dying green spacelady in an orange bikini in your yard, having crashed her saucer on the way back from an intergalactic disco boogie, don't let people put clutter in your yard in my memory. I think it's a distraction, tacky and frankly it's just a bunch of clutter.
LW#4: These friends of yours are going to lose a lot of friends fast if they demand their money for multilevel (ie pyramid) marketing schemes. So tell them that if they're after your money, you're not interested. But when they want to be friends, you'll be around.
As for your customers, I'm going to say listen to the P-dawg here. Stay tactful and upbeat, but for the love of all things holy, there is no reason on this earth to get that $40/bottle Mona Vie.