This is a difficult question to answer in a straightforward and helpful way. The simple answer about case life is; 'it depends'. There is no substitute for knowing what you are doing here. Generally speaking the hotter the load, the more severe the sizing, the poorer the brass, the fewer uses you will get. The variables I have actually measured that affect case life in my firearms include; how hot the load is; how the head space is in the rifle; quality of the brass; what kind of resizing one is doing and how you set your dies, e.g. neck size vs full-length resizing, partial resizing and so on. To elaborate a bit, I had a 303 Savage lever action that was my grandfather's rifle. It was very old with a 4 digit serial no. When you shot it using the mild loads, by modern standards, that such a rifle shot, the case stretched near the web and reloading was simply not on. On the other hand, I had a 7-08 that I was neck-sizing the cases for and shooting the mildest loads I could find commensurate with accuracy, and I easily got 8 uses per case. After about 8 uses the chambering got a little stiff and I full-length resized them and used them some more. I think most people would simply buy new cases after that many uses in that particular rifle. Cases aren't expensive and it certainly can't hurt. I'll leave the pistol reloading to pistoleros as I haven't done enough to know about case life though I have seen some things that would suggest such considerations may well apply in some cases.
As for cleaning the cases, I have wondered about this myself from time to time and I have seen as many different approaches as I have reloaders ranging from a quick wipe with a rag to hours of vibration. One main reason for cleaning, of course, is to avoid contamination of your reload, e.g. powder, primer. One source of contamination is the lube you use for resizing as well as the dirt it can pick up. An interesting idea I read years ago, forget who wrote it, was that one might clean cases too much and make them too slippery. I still have no idea if this is true and I mention it only for interests sake. I did just clean a bunch of 6BR cases and left them in the vibrator for an extended period (forgot them actually). They were very clean and actually quite slippery when I took them out. Maybe someone here knows more about this. What makes sense to me is to be reasonably clean. Get something that works for you and stick with it. One clearly doesn't have to go overboard. A couple of things to look for when cleaning: Be sure to clean the flasholes in your rounds after vibrating them in any kind of media. Use some form of liquid in your media to deal with media dust. I have used a cap full of paint thinner for years, but others do different things.