Spam comes in waves and we see tend to experience these waves at the end of weeks and the end of months. Spammers are always looking for new ways to get their links on our blogs. Currently they have hired humans to tell us idiotic things like they could not find out blogs by using their keys words, that we ought to blog more often, the our RSS feeds aren't working, etc. Experienced bloggers like you note when spammer are paid to feed our own words in our posts and comments back to us, but beginner bloggers are so desirous of comments that they don't spot that kind of spam or trackback or pingback spam either.
There is no FTP access and we cannot install plugins. Be ware that the Akismet Staff are on this and are continually updating Akismet's knowledge base.
Anyone can subscribe to the RSS feed on any public blog. Be aware that there are human beings who get paid to post spam as well as robotic programs that post spam. There's nothing unusual about what you are getting. We all get it.
The vast and overwhelming majority of all so-called information on the internet is spam. Over 80% of all so-called comments submitted to .wordpress.com blogs every day are spam.
The worst of all spam containing malware and viruses is not sent to us. It's removed as it could bring down many blogs if opened.
On the spam that Akismet catches it takes only seconds to click "empty spam" and you don't even have to click "empty spam" if you don't want to. Akismet will maintain comments it has caught for 15 days from the time they were received, and then it will delete the comment automatically.
If you get spam that slips by Akismet then mark it as spam (do not delete it) and over time Akismet will learn it's spam.
There is no such thing as eliminating all spam but Akismet works very well. For more information please take the time to read "5 things every blogger should know about spam" on this page Akismet: How it works http://akismet.com/how/