Yes. Power draw (both 'C' rating and running duration) may be an issue but I run brushless and brushed on both LiPo and Nimh. Nimh is on 'chugabout' as opposed 'racy' model. Some of ESC have DIP's/jumpers to select sources (3.0V cut-out for LiPo)

Yes, in principle.
Be careful of the power consumption. Brushless can consume many watts, which may be beyond the capacity of your cells