You have two separate issues here.
Feeds are not detected by browser, because information for that is not being output in page body. I believe the current way of adding those links is declaring it in theme with add_theme_support('automatic-feed-links'); in functions.php, see Feed Links in Codex.
Other issue is that something spits out unwanted new lines at the very start of output, both for your feeds and regular pages as well. Usually this is caused by such whitespace outside of <?php ?> tags somewhere in theme or plugin file, it can be rather hard to track down. functions.php of theme is always good place to check for this first.