Some questions about link cleanup

I had my website f**cked on 15 dec and everyone says i should low my main keywords density and i have a little question

When i log in on Majestic SEO and i ask for a Advanced Report i need to choose between: domain.com / www.domain.com / http://www.domain.com or http://domain.com
Aren't all the same ?
What i have to do to get a full backlinks report to know what to do ?

or another idea, i would buy social bookmarks/some seo packages with the most allowed keywords and fix the density thing, what do you think about that?

In view of Google www.domain.com and domain.com are different websites. Please take this into consideration for your future efforts.

Stay away from over-optimization i.e. Do not use your main keywords excessively in the anchor text links that you will create during the steps above. Be street-wise, avoid spikes in the number of your backlinks (do not buy one-time backlink packages), instead increase the number of backlinks smoothly. Sample Anchor Tex Link Formula: 20% - Your main keyword that you're wanting to rank for, 25% - Latent Semantic Indexing (LSI) keywords, 35% - Your URL as the anchor text, as well as other combinations of your branded keywords, 20% - Generic keywords. Google is now looking for a more diverse linking profile, a more natural one. The ratios are not perfect, just to give you a point of view.

I hope this helps.

Use domain.com from Majestic. That will give you all your links to all variations.

As far as anchor text over optimisation if they are spammy links remove/disavow them. If they are good links ask for the anchor text to be changed.

Don't get go creating tons more crappy links with random anchor text as it will just end in a manual penalty.