It means to get down to business, to get to the matter at hand, to get to work.
Brass tacks are commonly used to tack upholstery down to the frame. If you "get down" to the tacks, you have stripped away the upholstery and stuffing, and are down to the bare frame again.
Nothing. The phrase you want is "get down to brass tacks," which is an upholstery term. You tack the cloth and stuffing to the furniture frame with brass tacks, so if you are down to the tacks, you have nothing covering the frame. This idiom means that you cut through all the talk and go straight to the meat of the matter.
Brass tacks are what you see when you take the upholstery off furniture - the wood is traditionally held together by that kind of fastener. "Getting down to brass tacks" means stripping away anything not essential.
To do work and focus
Who creates idioms? That's pretty hard to answer. We can go back and see when the first appearance happens in print but newspaper and magazine writers aren't known for creating new words but rather mirroring an existing sentiment in the readership. In other words, no one would know what the idiom means unless the public already had exposure to its meaning. Idoms are created by storytellers, cultural groups and stakeholders of interests, clubs, religions etc, etc. On how an idiom gets created let's look at the idiom, Let's get down to brass tacks. When we look back and see how bolts of cloth, canvas and wire were sold in hardware stores we see that a length of rope was just that, the length between the owner's hands. Since these lengths were not uniform an owner or several owners put down markers such as tacks to measure yards, feet and inches. The first occurrence in the local paper talks about getting down to tacks, finally brass tacks. Obviously a saying that occurred in that locality centered around the one place most people would frequent, the hardware store. It caught on and came to mean getting all the facts or to flesh out many details. This is the way an idiom is created but it is the public that has to accept it before it goes into common use.
Distill down, or boil down, as an idiom, means to get to the essence of something, or to simplify it.
I've never heard that idiom before. Perhaps you mean DOWN AND OUT, which means that the person is at a low point in their life, that they're poor in every way and not likely to make a success at anything in the near future.
sit down come over to
This is an idiom meaning to narrow your focus down. It can also mean to narrow your aim and focus on one thing to hit. Picture the zero as a target and you get the idea of the idiom.
That is not idiomatic. The idiom is "elbow grease" which means "exertion" comparing it to a bottled product."You can get that brass to shine if you use more elbow grease." means "Polish harder and the brass will shine."
If someone "jumps down your throat" it means they react very angrily about something you said.
The idiom down to the wire means to the very last possible moment. Therefore, the entire phrase would stand to mean that "it went to the very last split second and we almost missed your flight, but made it."
This is not an idiom. The verb "lay" is the past tense of "lie," and means that whatever or whoever the subject of the sentence may be, they were laying down on top of some hay.