template design

Hello..
I am new in using WordPress and I have some minor problems.
I have a 3 column template design, the side bar in the left and the other 2 columns with articles.
I have some problems with the post showing on the front page.
1)I have 4 categories, and I want that post from 2 categories to show on one column and on the other column, the rest of the posts from the other 2 categories.
2) I use the function the_excerpt() to show the posts on the front page. Is there a way I can control how many rows to show from the excerpt of the article?
And If I have some pictures at the begining of the article, the picture is not shown on the first page. How can I have a picture in the excerpt of the post???
Shall I use another function to display the content of the article on the first page?
3) Is there a plugin that can allow me to modify the order of the post displayed on the first page? I want them displayed as importance, for example, not by date or alphabeticaly.

Thanks!

thanks