1. You can visit Canada. No issues.
2. There's no min or max really. It all depends on how many points you have. The higher your points, the greater the chance you will be selected. If you have 490+ points, I would expect selection within two weeks for example.
3. Because people hated the old system and complained about it non-stop, processing took far too long (people were waiting years), there were caps (first come, first serve approach), etc., etc., etc.
4. Depends on how you are applying for PR. Canada has a number of different streams. For Express Entry, you will receive an electronic checklist one you are selected. Information is also available here: http://www.cic.gc.ca/english/immigrate/skilled/apply-how.asp. Additionally, there are many very active discussions you can read through in the Express Entry section of the forum, especially the first three that are pinned: http://www.canadavisa.com/canada-immigration-discussion-board/express-entry-expression-of-interest-b54.0/