Font size impacts user experience and may impact SEO in certain cases. Providing users multiple font size options to choose from i.e small, medium, large helps user experience. Search spiders do look for usage of bold, italics and H1 tags on a web page. Better user experience generally lead to better SEO.

Ryan answered this question pretty well and I would like to add few points to it

1. As long as your site architecture is organic and designed for the user you should not be too concerned about page -keyword targeting.

2. Avoid have too many links on the page. Typically, there should not be more than 150 links on a page.

3. Make sure to have equal balance of content and images on the site.

4. Backlinks with good distribution of anchor text.

Directory submissions are a total waste of time. Personally, I would not use any software solutions that offer mass directory / article / comment submissions because these fall under grey area and search engines don't value these anymore like they use to years ago.

Local directory submission to websites like angielist, superpages, citysearch, yelp is certainly useful for local rankings.

Search engines are placing more importance to usability than ever before and longer URLs are usually not considered user friendly. The popularity of URL shortening service is another proof that having shorter url is better.

The idea is to maintain the right balance between keyword usage in the URL and the length of URL.

Best practice is to add new content and create new title and meta for these pages instead of changing title for the same page constantly.

Changing title too many times in short span can confuse the search spider as title is the first piece of content crawled by spiders. By changing the title too many times you may cause the search spider to think that there is something unnatural about the website.

What you are essentially talking about is creating offsite gateway pages. Gateway pages are definitely considered spam when done for the sole purpose of link building and ranking. Squidoo is not a bad site and we have many pages (lens) on squidoo and the pages have unique content. It is a good place to market your content and build personal authority.

If your squidoo lens is high authority and have ton of links to it then a link from that particular page to your website will carry some link juice. However, the goal should be to create good quality lens to help users.

It is also important to note that Google latest panda update has impacted the traffic and ranking of content farms and low quality content sites like hub pages, ehow, ezine article. It is quiet possible that squidoo has lost traffic as well because there are tons of lens that are low quality and were build for the sole purpose of link building.

Best

Sameer