Great! That loose plug wire and the corroded battery connections are certainly enough to produce random misfires. You should be good for quite a long time.

I like that it is a manual. Make sure you replace the brake fluid for both the brakes and the clutch hydraulics. Always take your foot off the clutch pedal and to the side after completing the shift. In other words: don't ride the clutch.

 

Dude Im sorry that has happened to you. I hope that gets fixed soon.