Theme development

Hello guys,

I am new to Drupal and CSS in general. I started playing with it few weeks ago and I am trying to make my first web site with Drupal. I have reached some level of success but I am mostly facing problems with the design in Drupal. I mean the way Drupal works is more or less clear to me but making the site also looks attractive is still kind of a mystery.

At the moment I am stuck in designing a fancy menu for my site.

What's the correct syntax to insert a view/views slideshow into a template file? Is there any resource where I can look into this?

I want to have a banner of rotating text inside a template, with the user able to add additional sentences for rotation.

As a -new - theme developer I have installed the Devel module, Theme Developer module which requires the simplehtmldom module.
Once I enable the simplehtmldom module, I get the following error ;:

Warning: file_put_contents(temporary://devel_themer/cs7fead19c53bea18a7e1b35e7c62bca4821668a06): failed to open stream: "DrupalTemporaryStreamWrapper::stream_open" call failed in devel_themer_store_krumo() (line 348 of C:\wamp\www\drupal-7.22\modules\devel_themer\devel_themer.module).

I am currently using mobilekey and themekey to switch layouts (themes) for a mobile site in Drupal 6. After a year, it seems on some networks mobilekey and themekey work 'sometimes' and on others they do not.

Is there an easy way to theme the web form? All I'm seeing is stuff like "<?php print drupal_render_children" etc.

Where would I set up like custom CSS files to determine how the form would look?

i am not sure if i have to theme views .tpl or theme ubercart 'add to cart form' to solve my problem.
Either way it doesn't look like simple answer, but at the same time the way it is presenting looks ugly.

In views i have field - Product: Add to cart form and style is table.