A few questions about the "random html page" code:
What "random html page" code are you referring to? I'm new here, perhaps I've missed something.
Is there a way I can have percentages/odds/chances for each random page to be displayed?
How many pages are there? If you had 10 pages and true randomness, then it stands to reason that over time each page would have a 10% chance of being displayed.
And, once someone is displayed any of these pages, is it possible to block their IP address from viewing that page until 24 hours?
Have a look at the HTTP header: REMOTE_ADDR. However this is not reliable, is easily spoofed and is often the address of a proxy server thus potentially blocking other users behind said proxy.