Answer I doubt whether there is any upper limit with modern browsers. There would obviously be a restriction when you fill up your entire hard drive with bookmarks but you are unlikely to meet that in practice What will limit you is your ability to navigate your way easily through hundreds of bookmarks, so the upper limit is really the capacity of your own memory!
Infinite. There are always new site being made. Impossible to count.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.