CPU - most of quad core hp 15 that I've seen have had the A8-7410. If yours has this you are out of luck. It is BGA (soldered to motherboard) and ... I believe it is the top processor in its family.
Ram - 'officially' the hp 15 supports 8 gb of ram. That is also said about the hp g6 but I know the g6 is ok with 16 - not sure if this is true for the hp 15.