1. A tags - stuffing them
I know that according to good CSS having div tags inside a tags is a big no no.
But you can have span tags, so I construct my specific a tag like this:

<a href="mypage.html">
<span class="title">Brand new article</span>
<span class="image" style="background-image:ur(myimage.jpg)"></span>
<span class="description">very interesting read</span>
</a>

I proceed by giving display:block and floats to span tags in my CSS file and you can imagine how it looks, pretty nice :)

So I end up with this "box" that is one big link. Looks nice, navigates nice.
But what about SEO?
Will Google be mad at me for adding all that code inside a tag?

2. A tags - titles
- Should I add "title" attribute to all my a tags? Even if I have something as in question 1?

3. Mighty Ajax
- I use it in many places. I don't overdo it, but I still love it:)
- I presume Google does NOT see what Ajax stuff I import to page right? No, I'm ok with that:)

You see, I had an idea to also use Ajax to improve how my page looks like from the SEO point of view.
For example I have a small gallery on my front page where you can click on the buttons below (1 to 10) to change the image.
The "Buttons bar" is simple, but it's a bunch of ugly code. So I decided to add that bar via Ajax when page loads.
My guess is that Google won't see it then ? (which I want)

4. What EXACTLY does Google see?
- follow up to my previous question.
- Does Google see exactly what I see when I choose "view page source"?

5. Can Google find this?
say I have this at the top of my page:

session_start();
if (isset($_SESSION['username']) AND ($_SESSION['username']=="justme")) {
echo "meaning of life is... coding !";
}else{
echo "meaning of life? Dunno, Google it";
}

Can Google's robot find out what is the "meaning of life"? Even if I explicitly state that only a user "justme" can have that bit echoed out?

6. Can Google find THIS?
Let's say I create a page lonesome.php, it's url is like this: mysite.com/lonesome.php
I NEVER link it, NEVER mail it. NEVER even talk about it :)
Can Google still find it? If yes, how the hell did he do it? : D
I know I can exclude it using robots.txt etc, but I just want to know :)

7. 99% of my images are actually background images!
Yep, I'm working on a "liquid" site and use percentages instead of pixels, that's why its much more easier to use css image-background then real img tags.
Is this ok with G?

I think these are some of the major things that were going through my head lately, feel free to comment/answer on any of these.
I'll lurk around now : D