Wedding photography running out of space. Need help with thousands of photos, and workflow

Question

So my studio does wedding photography. Me and my partner both take photos.  We have about 30,000 photos just from the last 2 years.  We are running out of space big time. We both have 1 terabyte magnetic hard drives in our computers. I have about 80gb left and she has about 120gb left. Needless to say, since I myself take about 50gb of photos per wedding, I'm not going to last long. We use lightroom.
So far I have managed to backup everything on an external 2TB hard drive for both of us. I save both RAW and Jpegs to it. I also have everything backed up on an online server.  So here's my first issue.  What I've been doing, is for the previous year (completed weddings) I delete all the RAWs from the computers. I leave the JPEG's on the computer incase I need them quickly. I keep all the RAWS on the external hard drives and online.  But even doing this, deleting the RAWs from completed weddings off the internal hard drives, I'm still almost out of space. My computer is so slow because of this even though it's a top of the line computer with 6 gigs of triple channel ram. Lightroom runs so very slow and lags so bad.
So my first question is:  By deleting the raws off of my computer, if I need to go back a few years from now and re-save the raw files or re-edit, will lightroom remember my develop settings or will I have to completely re-edit every photo?  I have been saving a catalog file for each year, and start a new one every year.  I do not use XMP sidecar files I save everything to the lightroom database.  As long as I have the catalog file backed up, am I safe? Or am I doing this wrong? Because if open an old catalog file, it will say all the photos are not found on my computer (obviously).
My second question is:  I am going to be investing in more hard drives and want to do it right this time around. I want to invest in SSD drives for maximum performance.  Here is what my plan is.  One SSD drive for windows/programs, one SSD drive for lightroom scratch disk, and one 1TB "Velociraptor" 10,000rpm magnetic hard drive for keeping the actual images on.  Is this not right? Am I planning this out wrong?
Here is our current workflow. I am very welcome to suggestions:
1) Shoot wedding.
2) Import RAW files from CF card to computer. It goes in a folder for the client with the images going into different sub folders by category such as "reception" and "ceremony"
3) Import folder into lightroom4.
4) Edit photos. I do not use XMP sidecar, I use database.
5) Export files in JPEG form into the same client folder.
6) At the end of the year I save the catalog, make a new catalog for the new year. I delete the RAW files off of my hard drive after backing them up on 2TB external hard drive. I leave the jpegs and the client's folder on the computer hard drive.

Answer 1

My guess is that you are not actually deleting the original raws from your internal hard drives and have lots and lots of crud around that you are not aware off so you should go through your internal drives with a fine-toothed comb. Don't forget to actually empty the trash when you delete! 1TB is more than enough disk space for storing the Lightroom catalog file, previews and some jpegs. 30.000 photos is really not that much. My main catalog  has >50.000 images in it with the raw files all stored on external hard drives. The catalog itself is on my internal 256 GB SSD HD that also houses the previews (so I can use it with the raw files offline) and the operating system as well as a lot of software (photoshop, office, iWorks, Aperture, etc.). It is more than enough space as it still has more than 150 GB free. I automatically back up everything, including the external HD that stores the raw images to separate external HDs stored in different places.