Right, after all the problems I have had with my previous site, I have decided to set up a new site on a new domain. Could you please take a look and let me know if you foresee any SEO problems (in particular with Google). The site is using Wordpress. The reason I ask is that my old site used to use TextPattern and was PR4 and had a few good rankings. Since changing over to Wordpress I now have PR0 and don't rank for anything. Anyway - as said this is a new site (in the same new layout as my other site). Hopefully it shouldn't have any issues - but please let me know if you spot any problems.
This is not correct. You cannot "create" PR on your own site but with the right internal linking strathegy you can "channel/send" page rank from your own site's pages to a specific page (most commen is to the main page) on your domain.
Just with a quick check it looks like you have the main things covered. You have already redirected the domain to www, using seo friendly urls and post title as the page title. You might want to consider using a Sitemap as posts can get buried deep within a blog. I use Sitemap Generator Pluging which is really good.