Hi, I sympathise with your problem. Had a hell of a time myself and this Building database schema seems pretty familiar to me.
I got SS to install and tried a number of possibilities I listed here:
Essentially, my tips are here:
Check your PHP version - should be 5. If 4, there's the reason for your problems
Check if "allow_url_fopen" is set to on. If off set a php.ini to switch them on
Get a command to tell your server to enable mod_rewrite (see my blog). Make sure it's right for your server / directories.
Go away, do some shopping, have a cup of tea, and wait for your host's server to update everything. Come back and see if it works