System Upgrade and Clean Install

First, some background. I went Mac in 2005 with an iBook running 10.4. Soon enough, 2008 rolls around, and I found myself with a new Macbook Pro. I Simply migrated my system to the new computer and went about my day. 2011 rolls around, and guess what? Time for a new computer again. Again, I migrated everything from my old computer to the new computer. So, here we are in 2013 now, and instead of upgrading my computer (It's still pretty current in terms of performance specs), I have decided to put in an SSD and max out the RAM.

Due to the nature of replacing a hard drive (With less capacity than my current drive), I know I'll need to split up my files (Some will be loaded from the SSD, most will reside on a traditional HDD). I also figured that 8 years of crap that has accumulated on my computers has to be creating all kinds of slowness in my system, so I have decided to do a completely clean install.

In short, here is my plan:

- Backup old HDD, do clean install of 10.8 on the SSD
- Format my old HDD
- Move my User folder to the old HDD (It's nearly 200Gb)
- Move my old files (That live outside of the Mac folder hierarchy) to the SSD
- Re-install all of my apps
- Hope for the best

During this entire process, I am mostly concerned with keeping all of my user data, keeping all of my files, but being able to essentially 'migrate' my system to the clean install without re-installing all of the junk that has been installed on my computer over the years. I want to be able to perform these steps, and upon booting into Mac OS after performing these steps, have my system essentially the same as it was before (settings, etc.), but with less junk that slows me down.

tl;dr
I want to do some hardware upgrades, perform a clean install, and not lose any of my data and settings, while at the same time having better performance.