-Will there be any more characters after Robo-Fortune? Can we kickstart more characters?
It depends on Lab Zero's situation at that time in the future. At the moment, everyone at Lab Zero is working at near-minimum wage, sometimes unpaid, to create the characters they promised in the IGG campaign; despite their love for the game and its community, this is not something they want to do again. Asking for more money (at higher, non-minimum wages) in a hypothetical second kickstarter has been brought up as an idea, and the general consensus at Lab Zero is that it would be too exploitative of them to continuously ask the community for money.
As of May 2014, barring further funding by Autumn or other interested parties, the current plan for Skullgirls post-Robo-Fortune is to submit some final bug patches/balance tweaks some time after R.Fortune's release, complete any promised content (hi-res sprites for PC, voice packs), and then let the game stand as it is, polished to the nth degree over 2+ years.