I was in a similar position to what you are. I finished uni, got a job for a few years then decided I wanted to do a PhD. The simplest answer to your question is simply look for projects you like and start applying for them, contact supervisors for more information on the project and explain your situation/background and see what they say. Some supervisors prefer to take PhD students who have been out working over fresh graduates. Don't see the fact you have been out of the academic bubble for 2 years as being a bad thing, you will have developed alot of skills that you can carry over to a PhD project; time management, working to deadlines and the like. It is also a good sign of commitment leaving the working world to come back into academia (usually with a decrease in salary!).
As for narrowing down the research topic, well you are on your own with that one. It is a personal choice and there are lots of things that can influence your choice of topic: University reputation, city, supervisor etc etc. My advice here would be to look for a topic which you really enjoy and focus on that in the first instance. The PhD process has alot of ups and downs and I know I would have struggled at times if I didn't really enjoy my subject. It can be a long and frustrating period looking for studentships so it is probably a good idea to start ASAP!