1) Depends on where you are at. In a very humid area a dry box or safe might be worth the expense. In most areas, just keeping your gear dry and never putting it away wet will suffice.
2) Not IMHO, but if you want to go ahead. Mine are in different sections of my camera bag. Some have neoprene sleeves around them which lets me stack multiple lenses in the same slot of the bag.
3) Depends on what you mean by 'clean'. I try to wipe the outside down and remove any dust every time I come in. But I rarely if ever clean the glass. I only do that if there is noticeable crud on it and even then very carefully.
4) I have a 135mm made in 1958. I used it to take the first image from my K-1. Worked fine. I'm sure others have even older lenses. Really, what can go wrong with the glass? Electronics might be different.
5) Only clean if needed. The camera has a self clean function that should be used, I have mine set to run on startup. If that fails to clean something try a rocket blower. If that does not work, then you might need a wet cleaning, which you can do yourself or take to a camera shop to have done. This usually costs $40 - $50ish.
6) No idea what that is
7) There are camera armor coverings for some brands, not sure if there are any for Pentax though. The usefulness is debatable to me, but if you are particularly hard on gear it might be worth it. I keep the camera in a bag all the time except when in use.
8) Probably, but I don't use laptops for any image processing, much prefer the 27" screen of my desktop.
Keep in mind though that answers to your questions will vary depending on: location, climate, camera use, and personal preference. Bottom line, there is no 'right' answer, do what you think is best for your situation.