Do I have a virus, a back door? Am I hacked?
I don't know who you are, but chances are, you're aren't relevant enough to warrant hardware tapping.
Macs don't really get viruses. There are some trojans (malware in disguise as user software), but they require the user to manually input their administrative password. If you're suspect your infected, try a virus scanner like ClamXAV, but I doubt you'll find anything. Apple does a really good job at keep up to date against malware. DO NOT install any sort of on demand virus software. Generally Mac anti-virus programs don't actually protect from Mac viruses; they're meant to prevent Macs for being a vector for Windows viruses. As a Mac user, it's very easy to download a file infected with a Windows virus, and unknowingly pass it on to a Windows user.
A much more likely explanation is some sort of system related issue. Can you please keep Activity monitor open, and enable its dock icon CPU viewer from this menu:

Keep an eye on the CPU levels, perhaps you'll find a runaway process that's using your system resources.