Well, as you can see from the graph your computer is doing not much else the first 25 seconds or so but wait for your hard disk to do what it is told. Easiest way to shorten the boot time is to replace it with a solid state disk (boot time is 6 seconds here).
The harder way to shorten the boot time is to load less programs at start up. For Linux Mint 13 I have some tips for that here, but you can probably pick from that and use it for Linux Mint 14 also: viewtopic.php?f=18&t=106417&p=600177#p600177
As to rcX.d directories, no, don't touch those. A lot has happened since Linux Mint 9... Ubuntu has been migrating from SySV init system, to its own Upstart init system. The wiki page for that may help: https://help.ubuntu.com/community/UpstartHowto
. I wouldn't mess with Upstart's own files, but instead as I show for Samba + Avahi in my above linked post, place an override file for the services you don't want to start automatically.