Yes, the chromed, case hardened rods are very different than the oil hardened (which are basically tool steel - not meant to have bearings running on them) You can re-use the existing rods if you absolutely have to, but they will wear out after a month or two...
yeah, the rods I linked to are 30in/762mm - they are meant to be cut to the correct lengths once you get them. a cut off wheel is going to be the fastest way of cutting - either on a dremel or an angle grinder. I used an angle grinder cause I have one.
You need 2 cut pcs for the Y axis (front to back), and 2 cut pcs for the X axis (left to right) - buying 2 of those long rods will yield 2 cut pieces each with just a little left over on each one - best bang for the buck that I could find.
Recommend you do just one thing at a time here - baby steps to get started.
Start with the glass plate & hairspray right away to eliminate any potential warp of the aluminum bed. that will give you a nice flat surface to print your parts on once you get everything dialed in and it is printing nicely. It is so frustrating trying to print on a warped bed - been there! LOL
Then print up the Lawsy Carriages & extruder and install those along with the new rods. Will make a world of difference in how smoothly the printer runs!
You will probably want to get a fan on the X motor if you are going to enclose it - there is a great little fan mount on thingiverse (http://www.thingiverse.com/thing:128526) - friction fit to the motor, you just need a 40mm fan to put on it. mine used to get so hot you couldn't touch them - this can lead to skipped step problems. With that fan mount/fan installed they stay nice and cool now.
There are a few ways of enclosing your printer - everything from basic cardboard to foil-backed insulating foam to acrylic panels. You need to decide what is going to work best for you.
SD4 #1 & #2 - Lawsy carriages, E3D v6, Rumba controller board, mirror bed plate, X motor fan, upgraded PSU & Mica bed heater
SD4 #3 - in the works ~ Folgertech FT-5, rev 1
Printit Industries Beta Tester - Horizon H1