98% sure that 10,000 is an arbitrary number, because people like clean whole numbers. In reality, I think you need 9873 sentences. No im joking, the point is that it doesnt matter - the more the better.
Yes, of course you can. In fact, you should probably be doing that on top of this. I think the strength of this method is to solidify any existing knowledge that you may have. After you have accumulated enough articles, you may forget which article a particularly good example was in. If you put it into SRS, you dont have to worry
If you try it and then it works for you, great! If it doesn’t then you are better of spending your valuable time via another approach. For me it seems to be working, though Ive only just started