Welcome to the Q&A Forum

You do not want to build a link profile with 100% do-follow links you can also include some no-follow to make the profile look natural.

Also Delicious has a great amount of traffic.

Ideally your home page is going to be your highest authority page, also target a few sub category landing pages with related content to that specific page.

Ideally you want to only target 3 keywords on each sub category page with related content to that specific keyword.

Directories are not that bad if they are related to the site, I would look deeper into the link profile, to me it sounds like a decent site if their is numerous quality content and they also have a decent amount of traffic and keywords driving traffic to the site I say go for it.