Your receiver should handle the speakers impedance. As far as power goes, Connect it up and try it. If it doesn't play loud enough at about 1:00 on the volume control (or when you here any sign of amp stress) with tone controls off with the FM radio, you may need more. In a med size room with the speakers in the corners I think you will be surprised at how well that Yamaha plays those speakers.
Back in the late 70's receivers in 20 wpc and under range were quite popular. My 10 wpc Realistic receiver drives my Energy C-1 bookshelves way louder than I normally listen to. Those Pioneer's are a little less sensitive, But I'm sure they would work fine too. If you want concert level SPL's, Than yes, you will need more power and probably more speaker. But most people over estimate their power requirements. Often I listen to my amp in the 2w meter range.