For the first question- installing- I just install Drupal 5.1 to fool around with, and it's really pretty easy-
Assuming you are on a Basic (Linux) plan, log in to cPanel, and go to MySql Databases- add a database (go down to the "new database" field)- name it username_databasename  (i.e.- your cpanle username underscore whatever you want the new database name to be- I would use something like username_drupal1 .
Next- go back and add a user- (create user)- I use the same name as the database name, and fill in a password (go back again).
Finally, go down to "Add  a user to your databases". choose the new user and add it to the new database.

Then- upload the whole Drupal directory to the directory you want it in, and navigate with your web browser to that directory (i.e.- if you upload to /public_html/new_drupal  enter www.yoursite.tld/new_drupal  ) and you will get the setup page where you have to enter the database, user and password names you just created.

As to the second question- I know it can be done- probably easily- but I'm not sure how (as I have just started with Drupal today). I bet folks on the Drupal forumas could answer that though...