Welp! I'm no expert, but I am a 3d kid so I hope I can help you out. I just graduated in the winter from the Art Institute of Philadelphia and it wasn't until late in my college career when I finally realized that I really wanted to get involved with the gaming industry. It was more pressure that was holding me back but, we don't need to get into that story. I wish I was able to plan ahead like your doing right now! But it's cool. Lately I've been really getting into the research and practice behind what I want to do, so I'm going to share what I've been learning with you in these way educational past few months.
Mm, I know your saying you want to focus on what you can do with the time you have. Drawing is definitely a good thing to continuously work on. I'd have to go with what Red 5 was saying. Draw all kinds of things. Practice drawing them in challenging ways too, to get perspective down real nice. Manga and comics are cool, but only because those guys worked hard to understand anatomy and facial expressions from real life to the point where they could distort accurately, if that makes any sense. Traditional skills are essential.
Do a lot of research over the next 3 months as well. Figure out what aspect of the industry you have a passion for and began taking steps toward mastering it. For example, narrow down if you want to be on the 2d team, the 3d team or the design team. Then, figure out if you want to be an environment artist, or a character artist, or a level designer, etc. There are lots of different areas and it would be great if you were accomplished in many. But for the most part, the common case is that in the gaming industry you are part of a team. So most likely, folks hiring are looking for people talented and passionate about a particular thing so they can stick you in the pipeline. One character gets touched by many different artists, all experts in one particular thing. No one artist will model, texture, light, rig and animate one thing all on their own.
So yea! If you already know what you want then go for it. But it looks like your not sure yet. You've got some time to figure it out though, but it's important that you do. It will make the path less foggy for you once you have a clearer goal in mind.
As for Maya tutorials. I'm not too sure about where to find good free ones. But Digital Tutors and Gnomon make some awesome training DVD's.
On the side, here's a few more sites to add to conceptart for inspiration:
I suggest you get into ZBrush a little too at some point. Doesn't have to be during the summer. But you can download a trial version and there's tones of free tutorials right on the site. I think a program like this is going to be a must in the next few years, if not sooner. But that's just my opinion!