Drupal 7.x

I recently had a website designer create a website for me using Drupal. I currently know nothing about website maintenance, but I would like to learn how update my site's text now and again. If it helps, my site is hosted by Godaddy on a Linux server. My question is: where do I start? Do I download Drupal to my computer then upload the site info onto it? I apologize for my ignorance :-)

Is there a way to access the content type in page.tpl.php?

I haven't came across a module nor program that reads the entire root folder and/or database for lines that are unused and may be deleted. Or some checklist where you can select 'things' you want deleted. Like deleting all "/* */" lines.

Some "Cleanup" program?

Is anything known about this?

Where can one find a complete list for Drupal 7 theme variables. For instance the url fragment for the current theme (when printing out pictures and stuff for the current theme)?

I have created a content type to use for e.g. http://vih.dk/fag/fodbold. I have a title, description and a picture. I want to access the picture in an exact size in my page.tpl.php, as it has to be printed out in the css for the design to be solid. How do I access the individual fields and exactly the correct picture size in page.tpl.php?

I found out how to choose which page to use as a frontpage on admin/config/system/site-information. However, I want the frontpage to be special layout. How do I use a special layout for exactly the page I choose to be my frontpage? Thank you in advance!