All I can say is that I meditate every day for at least 20 minutes per session, usually in the evening or before bed. It has SEEMED to improve my rate of lucidity although I cannot provide any concrete evidence. Along with the things you mentioned, meditation also helps with awareness, which is key for realising you are in the dream state. If done diligently, the awareness you gain during meditation sessions will spill over into daily life. You find yourself being 'in the moment' more often and generally just being more in touch with your immediate surroundings, which obviously is going to help a great deal in gaining lucidity.

I know nothing of the effects it has on sleep cycles, except perhaps that once I managed to fall into sleep paralysis and enter lucidity just after going to bed (at night). This could have been for many reasons though as I am used to experiencing REM rebounds after working night duties on the weekend.

I think thats all I have to say now, interested to hear other replies.

Dunc