Will this work for getting dry erase marker out of fabric? Micro suede couch to be exact!

i haven't tried that but it worked for grease from a workout machine at my gym. All these carbona are great, in my opinion.

will this remove black ink from a printer ink cart from a carpet ?

Well it has been awhile since I ordered this product, but I do not believe that it will remove ink from carpets very well. The following link is something I discovered and tried on a small ink stain on a carpet stain and it removed it. Here is the link to a YouTube article that I have tried and it seems to work just fine. https://www.youtube.com/watch?v=DHUQAZFdTOM The video article is for cleaning print heads, but I would try it on the carpet stain. The price is reasonable since it uses common house cleaning agents.I tested it on a carpet remnant and took some pictures of it, but Amazon has no way of inserting a picture here. So I recommend checking out the video clip. I feel that this formulation works as good on this type of staining as the Carbona product. You may need a sponge to help remove the stain and you may have to work at it a little to remove the last 1 or 2 percent of the stain with either the Carbona or this mixture I have suggested here. Recommend to try blotting first, as this should not spread the stain as much as rubbing does.

will this work on ink stains that have been washed and dried? If not what doesn't work?

I've used this product many times on ink marks on shirts and jeans. It may not work the first time but will after a couple of trys. Best inmk removing product on the market.

does this remove ink stains off of floors?

Not sure...probably depends on what type of floor. I would get this info and contact Carbona. Or just buy it and try it on a unobtrusive area, as a bottle is less expensive than a new floor!