Yes. At now you can use MuLab DAW with its sequencer and piano roll in Renoise for an affordable price (cheaper than FL Studio). I have tested and worked together seamlessly.
Not sure about that. I haven´t tested yet. But you can of course record audio in Renoise, save to file and open in the MuLab plugin.
I am not MuLab user, but I like what is possible now. For those who want a full featured sequencer and pianoroll inside Renoise tracker this is the very nice and relatively cheap way.