Your 2011 iMac is likely as far as it can go with respect to the operating system version, and with the version(s) of Pages (Apple's current in-house WP application) that will work on it. If you have ever had the iWork applications, Pages, Numbers and Keynote, installed on this machine, you may be able to update to a suitable version by going to the App store and clicking on Purchases. If you see Pages in the list, there's a chance the store will offer an update.
(Viking OS X is more familiar with this, and may drop by with more detailed and better information.)
Another (free) option is to download and install LibreOffice, an open source application that includes word processing, spreadsheet, presentation and database front end modules.
There are also other WP only apps in the App store, with a variety of prices.
Regarding//the//keyboard//issue,//the //double//slashes//are//and//interesting//workaround,//but//not//all//that//practical//if//you're//communicating//with//other//people.
Take a look for a plug in keyboard. The wireless ones use Blue Tooth, and will likely require a newer version of Blue Tooth than is installed on your machine. We were lucky enough to get an Apple Extended keyboard from a friend who had just replaced his vintage Mac mini with a new laptop, and had no further need for the old (but still working) Apple Extended. You may be able to find one on the used market.
Best of luck in your search!
Regards,
Barry
