Im thinking of doing the same (except my late 2012 has a 500MB drive). As I am clueless with computers can I ask:
1. which ssd did you use?
2. which tutorial did you follow?
3. why not add the sad as a second drive?
While I can't answer for him specifically, I can help.
1) The brand of SSD isn't important, provided it's a reasonably current model (say last 2 years) and has enough space for your applications and files.
2) You don't need a tutorial, since the workflow is reasonably obvious:
Back up your original drive, preferably both using time machine and by saving the data separately for manual restoration if needed.
Make sure you have your OS version of choice saved on a USB.
Remove the bottom of your macbook using a screwdriver with the correct bit (check online for what is required, since Apple changed screw types between models). Retain your old drive.
Remove the retaining bar (single screw) that holds the old HDD in place and lift out & unplug the drive. Swap the 4 pegs from the screw holes across to your new drive.
Pop the new SSD in place, replace retaining bar, re-attach base of laptop.
Boot the macbook and install the OS from your memory stick.
Restore applications and data from your time machine backup.
Enjoy.
3) There are many times when a DVD drive is essential, let alone useful, and external drives are clumsy and inelegant. My present (non-Apple) computer needs an external DVD drive, and it's a PITA.