Yeah, it's probably set up for that little 4 battery pack like what's used on nitros. They make a rechargeable hump pack that fits in the same space but more reliable power. Like this.
Powerhobby 6V 1600mAh NiMH Receiver Hump Battery Pack Fits : 1/8 1/10 Losi T-Maxx HPI Ofna Mugen Kyosho...
Yeah, the one servo is going to be huge. It's trying to move sails against the wind. I did find this. It shows what comes in the RTR version. Scroll down. You can use the the specs to maybe find something comparable. You're also going to need a 4 ch stick remote...