Hi Ian,

I have a couple of questions:
1-do you need all of the inputs on the Yamaha MG12XU mixer?
2-is the Yamaha MG12XU mixer an audio interface, commonly called a sound card?

I don't think that the mixer is an audio interface. There are a number of audio interfaces available at a wide variety of prices; the price often depends on the mic preamps and the number of inputs needed. Many people here use Focusrite audio interfaces. If you only are going to record your guitar and sing simultaneously then all you need it this one:
https://www.sweetwater.com/store/detail/Scarlet2i2G2

Most of the time you may record each track individually. You would record the guitar then record your vocal. Don't worry about mixing as most all, if not all, DAWs have mixers built in. Also if the Yamaha is not an audio interface then you will have to buy one anyway.

The only other thing you will need to start is a pair of near field monitors. PC speakers, headphones and stereo systems do not have the flat or near flat response needed for recording music.

I do not use RealBand, I use Sonar as my DAW, but I have played with RealBand. My guess is that RealBand is more powerful than the Yamaha tied Cubase AI. Note be careful of DAWs that are tied to certain hardware as they are proprietary. You can get non-proprietary entry level DAWs from Sonar, Cubase and virtually every other DAW software out there. But since you don't have a favorite DAW right now I strongly suggest you use RealBand. Not only is it a powerful DAW you also have the most knowledgeable and friendly people here on the forums to help you if needed. To me these are the most important things to someone new to recording and DAWs.

{EDIT} I see a couple of others answered as I was slowly typing mine.

Last edited by MarioD; 05/05/17 02:09 PM.
Whenever I get something stuck in the back of my throat, I dislodge it by drinking a beer.
It's called the Heineken Maneuver.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware