1. Yes, as long as they are not personal links (blogs, advertising, stuff like that). Linking to things like potential components, images for illustration, etc are fine. If you post a link and the post vanishes it means one of our anti-spam modules flagged it for moderation... we will approve it as soon as we see it.
2. As a new member you can only have forum provided avatars. Check out the forum rules (at the top of every forum) for a full rundown of the privelege schedule as well as the rest of the rules.
3. Check here
for that code as well as a bunch more.
Great to have you with us, mate.