yaix2 - 10:30 am on Sep 9, 2010 (gmt 0)
1. SEO is, I realise, an ongoing thing that needs to be done very often and there are several ways of achieving a higher ranking
Good content that people search for and a technically correct site with no broken links, no duplicate content, no confusing layout or structure, and meta information users like to click on. That's mostly it. For the following few months swap some links with related sites.
2. I've just had a call out of the blue to get a sponsored listing right at the top of the page for a month for £120. Is this a good price?
It's probably a good price for the seller. However, if the mail came from Yahoo and the page is their homepage, it would be an awesome price. If it came from some link directory with tons of spam (more likely) then even £0 is not.
3. How do you find out when Google has changed their algorithm?
Look at your Analytic stats (or your AdSense/Aff income stats or bank account). Or have a look at your search terms in GWT.