-You'd want to keep both your email used for your Baen email account (obviously) and one or two of those throw away emails. You would want to use one (you only need one) of the throw away accounts for PM'ing to people in order to get the certificates/codes. You may want to use a second throwaway account to use for holding codes (if you're at the end of a chain-you may need to keep the throwaway code for up to a year until they expire) in order to keep the holding codes separate. Or, instead of the second throwaway email, you could ask someone on the boards to hold the codes for you so they won't be lost.
-I have two extra emails I use (as stated above), plus the one registered with Baen. I believe you may need only one extra email address (not registered with Baen) in order to get the Bundle certificates/codes and to hold codes. I just prefer having those in 2 separate emails.
-If anyone has any information to the contrary please chime in.