Search Function, Attachments, Link generation and other stuff…

Hello everybody,
thx for reading my topic and hope you can give me an answer =)

I will completely rebuild my wordpress and will create a complete new theme. In this case i have now different questions to a few functions of wordpress…

First, my full “test area” is running with an own database and with an own domain, so i can test and set up everything like i want. If you want to take a look of my testpage (i hope it helps you to give me answers) here ist he link: dev.eeel.ch/wp/

Now my questions:
1.) Searching tags and keywords – why wordpress doesn’s search for tags and keywords too? Is this an bug? and if not, why doesn’t? How would it be possible to solve it, that wordpress will search for tags too?

2.) Linking and unlinking attachments – if i’m uploading a attachment, f.e. a picture to a post, it’s directly linked to this topic. Is it possible to unlink an uploaded attachment? I know its possible to link an not linked attachment to an post, but why isn’t it possible in the other direction?

3.) Generating link to attachment page – i’m using this plugin (List Related Attachments) to show up all attachments from a post in the sidebar. I have edited the plugin a little bit, so i’m able to show the images directly as an images:

echo '<li '.$mime_class.'><a>ID).'" '.$link_target.'><img width="200px" src="'.wp_get_attachment_url($attachment->ID).'" alt="'.$display_str.'"/></a>';

My question is: how can i get the link to the attachment page? So if you would click on the image, you will be linked to the image and can write a comment or else.

That’s all at the moment, and i would be really happy if anybody could help me. I would be happy with a link to a plugin or good description too =)

Thanks for reading and have a nice evening.
derElch