As far as routine cleaning and maintenance goes, you really don't need to do alot. A drop of lube on the pivot points once in a while, a quick wipe of the exterior with a silicone gun rag, and that sit. The seal is synthetic, so chamber oil isn't needed. Cleaning the bore is something that should be done only if really needed. You may want to run a few patchesd soaked in Simple Green through it if its new, but after that if you shoot it regularly there isn't really much need to clean unless accuracy starts to degrade. That shouldn't be for quite a while for the casual shooter, maybe after two or three thousand shots.
As far as the service contract goes, it's not really worth it. I've heard many horror stories about what Beeman currently calls "customer service". Those HWs are real easy to fix, and better quality after market seals and springs are available for less than the cost of the inferior factory parts ( HW piston seals aren't so hot these days, neither are the springs). Any major failure (broken stock, bent barrel, etc) will most likely be pegged by Beeman as being caused by the customer and you'll end up paying for it to get fixed anyway. A bent barrel can be straightened pretty easily. A broken stock will cost you near as much as the whole gun to replace if you get it from Beeman, where as a JM custom DIY stock will cost you anywhere from $170 for a replacement piece to 270 for a nice tyrolean custom with Pachmayr butt pad. I would save that $50, and put it towards getting the gun tuned properly. If you think it shoots nice now, get it tuned and you'll never put it down.
