Ok, so how does the "series" part work.. thats what I really want to know more about.

whether its Deans or banana's the actual connector isn't too big a deal, I just wanna make sure I have the right Pos to Neg connections setup both between the 2 batteries and then to the Esc itself.

I have 2 hard packs now, but they both already have Deans on them.

I order 2 more hard packs, that will take banana connectors. This will be the setup going forward and the other 2 packs that already have Deans, will become my nitro starter box batteries and replace the NiMh packs to get more punch