Congrats on your purchase!

For heaters it wouldnt hurt to get the 250w pros (unless you are southern california where the heaters wont even be on much. I know you could get an inline heater heater if it matches up with tube size on the fx5 but I dont know much about them. The aqueons have a nice lifetime warranty and should be cichlid proof.

Your filtration plans look really good too. Depending on what you stock you could probably do less even. Though I would still keep one aquaclear 110 for surface movement and ease of getting at media or adding carbon if you need to.

I am assuming you wont have many plants with the devil so if I were you I would definately try out the light you have before you buy new. You would only have one foot on each end without light and it may spread enough for viewing. You can always upgrade later.