Assistance needed to Tweek existing site!

Hi All, 

I already have a Dolphin site that I'm quite happy with but there are a few small modifications that I would like to make to be very happy with it, these are:

- Adding a welcome page (only for subscription & login) - right not it possible to see all on the main page and I want it to be blocked so people have to subscribe before getting access. 

- my favicons do not work, I uploaded some to be selected by users who do not have their own pic, but it doesn't work.

- better facebook and twitter integration 

- SEO integration (I want to site to be crawled by the main search engines)

- thumbnail images to article, blogs, news that appears on frontpage

- setting up of paid membership, paid ads and paid classified (membership free for the first 500 subscribers)

I built my site myself but it took me a very long time to figure everything out, as I don't have that time as I would like this to be ready for June, I would prefer for someone who knows exactly what to do to assist with this. 

I would also appreciate any suggestions that you may have!

Many Thanks