equalling out columns to the bottom of the screen and more….

i’m currently working on a new wordpress template,
and i’m having trouble having a few issues.

first,
i’d like it if the main column and the sidebar extend to the bottom of the page and that there is no bottom margin for both columns. i can see this being tricky as the page length would probably vary depending on the blog entries. how can i have it so that both columns extend to the bottom of the page, without cutting any posts off.

secondly,
is it possible to create a page, where it brings up posts from specific categories. i know you can select a category and it’ll bring up the blog entries from that category, but i would like it to display as a page, with its own subheader graphic and a description before the posts show up.

the link to my blog is here:
https://www.black-rap.com/blog/

any help would be greatly appreciated.
thanks!