[nolok]

You're mixing a lot of things for no reason, the problem you describe really have very little or even nothing with open source or proprietary or even OSes.

Points 2/3/4 are exactly the same on other OSes, even open sources ones.

Point 1 might be easier to answer by yourself/someone who is not the vendor with open source OSes, while for Windows or OSX you depend on the vendor to tell you with certitude "starting with X" (which they always do). But on the other hand the centralized and streamlined patching model makes it much much easier to identify just which patch caused it, compared to "which level of package mainter or upstream caused it, is it a flaw in SOFT or in debian's SOFT-up3 or what ?"

Point 5 has nothing to do with open source either, on either you can easily test if it's fixed or not. Whether it's considered bug of feature-wont-fix is pretty much always answered so you don't have to actually ask yourself (but if they do consider it normal then you can't fix it yourself on closed source proprietary, though they usually give you a config change to get what you want).