I don't make starters. I don't do liquid yeast and I've been read/told that it's not good to do starters for dried yeast.
Now, are you telling me that if I was to brew batch A which had yeast strain X and then brew batch B which also was to use yeast strain X, I could simply dump the cooled wort from batch B into my primary bucket and if I do this, to avoid overpitching, I should just scoop out like 3/4 of the crud in the bottom of the bucket and pour the wort from batch B on top of the remaining crud? And then refrigerate the other 3/4 of crud and save for future batches the use yeast strain X? Thanks for the help! If this is true, then I guess I'd only have to buy yeast like 1 out of every 4 kits then huh?
People do all kinds of different things, and the argument over dry vs liquid is no exception. I use both, and IN MY OPINION you should build a starter, or pitch multiple packages, of LIQUID YEAST, depending on the gravity of the beer. Aeration is also recommended.
For DRY YEAST I recommend rehydrating, but aeration is not needed, and a starter is fine, but for the price, usually not worth the effort compared to buying a second packet, plus you have to then aerate as the yeast have used up the sterol reserves they built up during the drying process.
Note that this is just what I've read from the book YEAST and from the yeast manufacturers' own websites. My actual experience is that as long as the temperature is good for the yeast, and you give it food to eat, it will all work. I like to use best practices, even if I don't personally notice a difference on every batch.
As far as yeast rinsing and repitching, then yes, you could do it as you outline. Find out the optimum pitching rate and save that in the bucket. Scoop the remainder and rinse it. I've actually mostly gotten away from rinsing. I have no interest in brewing as a living and my time is precious, so after playing around with rinsing yeast I have had my fill. If I had a "Special" yeast and knew I were brewing more batches in a few weeks I'd consider doing it again, but for now I simply buy extra packets of dry, or build a liquid starter if my gravity is above about 1.060 or so. For most Pale Ales I find dry yeast works well and is really easy to keep and use. I rehydrate using sterilized water I've canned previously.