Drupal 7.x

Hello,

I have just installed 7.0 and am already stressing over confusing information.
Many similar CMS state to delete install files after installation, should that be done with Drupal? I can't find it mentioned anywhere?
Also in trying to search for post installation security measures I came accross conflicting info;

Step 3: The settings.php file

No. The correct permissions you should return to after this is complete are the following:

chmod 644 settings.php
chmod 755 ../default

Back when i used drupal 6 i could use a nice little module called node_import however i have moved into drupal 7 and now cant find any modules that would perform the same task, i have over 10,000 nodes i need to create and have all the data stored in a csv file. Any ideas anyone?

I've changed the row colours for tables in style.css which show up fine in IE. However the colours are not appearing in Firefox, they just show the default grey. What would be the best way to resolve this. I'm sure it's something simple, but I can't figure it out - ususally Firefox displays everything really well, and it's IE that's a bit crappy:/

Where/How to limit text size of content Title & Body of any content type ?
I could do it in Drupal 6 but didn't find any option in 7.

Hi, I copied the Bartik directory and renamed it as I want to make some changes to the styling via style.css. However, when I try and view my site after activating the theme I get the following error message:

Fatal error: Cannot redeclare bartik_preprocess_html() (previously declared in .../themes/bartik/template.php:7) in .../sites/all/themes/bartiktwo/template.php on line 28

I can't seem to work out what the problem is. From the documentation and tutorials I've seen here's what I did in total: