What could have caused my newish Macbook Pro that is usually reliably awesome to spaz out? What can I do?

Like a masochistic dork I installed an app called SelfControl on my three-month-old 15-inch Macbook Pro that I love and cherish to prohibit myself from accessing time-vacuuming sites while writing papers and studying for finals. The app lets you create a list of sites to "blacklist," and then prevents you from accessing them for the duration of the time limit you've set. Normally, the app works perfectly. For some reason, a couple of weeks ago it malfunctioned, and ever since then my laptop has been having tantrums. The timer wouldn't run out, so all sites I'd blacklisted were blocked for days. Even uninstalling the app and rebooting failed to lift the bans. Then, last Saturday the images on the screen became fragmented and frozen, and the laptop wouldn't let me restart it. I just unplugged the battery, let it completely die down, then plugged it back in and powered it on. It took considerably longer than usual, but the laptop did finally turn on. The really odd thing is that my screen image had changed on its own. Everything else seemed to work smoothly, and I could hop on to all the sites previously barred. Then one morning I woke up and the battery was totally dead. It won't take a charge now. Previously the battery health had been listed at 89%. Now it's 0%. This means that if the laptop is untethered from the cord for a nanosecond, it dies. It is also far more sensitive than before, and will sometimes just power off when I'm repositioning it on my laptop desk even if it's still plugged in.

Other oddities:

~ Sometimes when I log on the date will be listed as December 31, 2000, and apps won't function properly.

~ The system takes much longer to boot up

I admit to having mistreated the laptop a little, but it hasn't been seriously abused. I've never dropped it, and I never download torrents. I wrote over 220 pages in one month for five papers (college student), so I basically had it on nonstop. I kept it plugged in too often, which I know diminishes the battery power. A couple of months ago there was a tiny amount of liquid spilled on it accidentally, but the kind gents at the Mac store thoroughly examined it then and said no serious harm had been caused. Most people on my campus have Macs, and most of us have also been overworking our laptops, but none of my friends are encountering this problem. A ton of people use SelfControl without any woes.

Sorry my question is so long. I'm seriously wordy when I'm tired, haha. I am planning on posting this question in Mac forums and on the Apple discussion site, and I'm going to make an appointment for the Genius Bar. I would just love some feedback now. Is there anything I can do to fix some of these issues? Could the SelfControl app be responsible for these problems?