Oh oh, sorry, got mixed up somehow between the original post and your reply on level10guitar's thing. I'll just trim that part out of my post then...
I wouldn't say you need to worry about obeying any conventions. An extremely wide range of musical styles and writing/production techniques are encompassed within VGM, so I think most of us are accepting of a lot of diversity in sound and genre. One trend does stand out though: many of us are unhappy with the move toward imitating Hollywood scoring styles in game music, i.e. less melody, more "epic". This afflicts Western games the hardest and I think the fact that the large majority of attention here is given to Japanese music is due to that.
As far as mixing goes, you appear to have a pretty good grasp of it already. Generally, just don't try to make the volume blast constantly and use a limiter for peaks that want to go into the red and you should be pretty free otherwise. It's preferable to have a specially designed listening room and studio monitors with a frequency response as near to flat as possible, but of course lots of excellent-sounding music has been mixed in less than ideal conditions. And with as bad as many professional releases sound it's not that hard to seem alright in comparison. There are places like
Gearslutz where you can get more specific tips than "do what sounds good" about things like using EQ and other effects.
I'm sure that if you want to record guitar that your Pod must be able to get better sound somehow. I know Brendan Small recorded the music for the first season of Metalocalypse through a Line 6 Pod. I can't really give you any advice on it though since I don't have one.
And of course I'd be happy to give you my assessment of whatever you come up with next.
(One more suggestion: turn the lead instrument up in the part that starts at 1:08.)