Which template tag to use and more.. :)

I’m in the proces of turning my WordPress site into a fulltime photoblog and there are two things I’m not getting to my liking. ??

1. I’d like the front page (where you enter my site, the index) to have a link to the previous post, which tag to use? I’m using <?php previous_post_link('%link', '‹‹‹'); ?> which works great on the separate pages, just not on the index.

2. I’d like to have a commentform that does not show on the separate pages, only as a link next to the post title.

Ehrm…help? ??