You run a weekly defragment? That is insane, you are wasting your time doing that.
That feature has been built into the Mac operating system for many years…
http://support.apple.com/kb/HT1375
The OS does it in the background every time you save a file. It makes sure it is stored in the best manner possible. Files over 20MB are written to continous sections of disk.
Infact a defragger can reduce performance because it fights against the system's built in optimizations. The OS keeps important system files on the fastest part of the disk - the defragger can completly ruin that. Sorry to sound so blazé, but this is not Windows, treating it with the same system management ideas will waste your time & money.
ClamXav is a free antivirus scanner that I use to detect any potential threats. It doesn't add a ton of extra tools that really are not needed on a Mac, it just focuses on antivirus/ malware detection. You can run it on demand, or on a schedule or make it read every disk you connect (overkill & anoying).
http://www.clamxav.com/
I really think Mackeeper could be making you do things that are not needed.
The old applications don't really use any 'system resources' until you run them (like RAM & processor time), they will be taking up extra disk space, which could be better suited to files you use, so either delete them or move them to an external disk if you want to keep backup copies. Hard disks that spin (old style disks) tend to read & write data slower the more full they are, so leaving them 1/2 full will be quicker than 3/4 full. Removing items you don't need will help keep you in the fastest part.
I think you could do with some more advice on how to manage you Mac, and because this topic is not related here is what I suggest…
Read the Mackeeper threads & decide on if you think it is valid software, review the parts you use most often, post a new question along the lines of "What system maintenance should I do on Mavericks" & explain a little about what currently you do (with info on how often & see if everyone does similar things.
I know people who never run system tools, antivirus or defraggers on their Macs and they are completely fine.