This is user configurable in the <YourGameDirectory>\db\misc.txt file. To change the value from 20 IC increment just search for _RV_SLOT_IC_INCREMENT_ in the file and change its number. Beware, if you do change it, it's affects all countries.As for having at one time more than one tech team active (i.e. researching more than one thing) one needs at least 20 base IC. And then every 20 base IC will net you a new TT slot.