So, when this one is finished, I start another with 800001 to start from there, how do I up the amount of space it uses? I want to make it use more.
Yes, basically. 800000 generated nonces is about 200gb, since they're 256kb a piece. You can make multiple plots by upping the numbers in run_generate, thereby increasing your used space in total, or you can choose to make one giant plot by calculating how many space you're willing to use and how much nonces you'll need to fill said space, and then inputting those numbers in run_generate.
I guess basically all I need to know, is how to add more hard drive space to the mining... or whatever you would call it...
Do I start over with 800001, or do I make a new one with 64000000 or something else larger?
Your last nonce generated +1 should be the starting point you put in run_generate, so if your last nonce is 800000 you input 800001. You just keep upping the number to generate more nonces (and plots). You can also generate a huge plot at the same time by replacing 800000 by, say, 8000000 (8m). This would use about 2TB. (Unless there's a size limitation I'm unaware of!)