3 is correct, but it might also be easier to say "Yesterday I bought a meeting table with 4 legs" or just "Yesterday I bought a meeting table" (4 legs is implied when you are talking about a table).

"On my own" would mean by myself, though as others have said, that sentence has many issues. I think it meant to say either "There are a lot of things to do on my own" or "I do a lot of things on my own", it's hard to tell which without context.

Definitely the second sentence (What would it take for you to...). It may not be technically correct, but it is definitely the way you would expect to hear it in normal speech. There is also (as you mentioned) a strong tone of underhandedness or less than reputable business associated with the phrase.

Occasionally you will hear people (at least in English, no idea about other languages) turn a noun into a verb, meaning to become either like the noun, or to describe a state of having something to do with the noun. It's often improper, but it happens (I myself am guilty of this on occasion). There are some instances as well where this has become correct (to brown a piece of bread for instance, means to cook it until the surface turns brown). Another example would be my "Before I start work in the morning, I have to get coffee'd up" = "Before I start work, I drink a lot of coffee"

Well the video was talking about voice recognition, so in this case I think the poster of that comment actually mis-spoke. I would think "Video Relay Service" would be unlikely, since it's not well known among hearing people (I personally had never heard of that before). I think the poster mean to say AI (Artificial Intelligence), and has confused it with VR (Virtual Reality). Virtual Reality (VR) was a buzzword back in the 90's referring to very realistic computer generated environments (3 dimensional video, tactile interaction, etc.). While it's incorrect in this sense, I can see how the confusion would be possible.I believe what they were actually referring to, is voice recognition software, which they meant to (incorrectly) call AI, but came up with the (incorrect) acronym VR instead.

I depends on context as well. For the year 1900, it would be extremely odd to say it any way other than "nineteen hundred". For the number 1,900 either "nineteen hundred" or "one thousand nine hundred" would be typical. For clarity (like an address for instance) it could also be said "one nine zero zero", though this would be less common in my experience.