Since your phone is MarvelC/CDMA, the easiest way to root it is by getting S-OFF. Don't worry about unlocking the bootloader. Get S-OFF, then root. See the procedure in this thread:
Tutorials, Roms, Team MarvelUSc -- EVERYTHING YOU NEED
Be careful deleting system apps since deleting some will make your ROM unstable giving you a much greater headache. After you've rooted the phone and before you make any chances to the ROM, I (very) strongly suggest that you install a custom Recovery and backup your ROM. See steps 5A and 5B of this guide:
[Guide] How to root the Wildfire S with S-ON (finally!)
Make sure that you get the recovery for MarvelC and not Marvel. They are not the same.
Since your main goal is to get more memory, make sure you spend some time moving more user apps to the SD card which is easier with a rooted phone.
Hope that helps!