Re: NOOB ALERT: Questions for starting out..
That looks to be the same huge frame that my Schwinn Timberline MTB has. I have a Schwinn High Plains too and the frame is about 8" smaller.
I'd definitely look for a cheap used MTB to steal the handlebars, shifters, front shock forks, wheels tires off from. Those skinny tires will make for a very harsh ride @ 30 mph.