The Motion Plus accessory is a component needed to play Wii Sports Resort.
Wii MotionPlus - Wikipedia, the free encyclopedia
The version that comes with Wii Sports Resort is sort of like a WiiMote condom--it has the block that attaches to the bottom of the WiiMote, and then a silicone skin that fits around the rest of the WiiMote.
We use rechargeable batteries with our WiiMotes. Easy enough. We almost always have 8 spare batteries charged up to swap into the WiiMotes.