Bode plot, nyquist, root locus

Bode plot, nyquist, root locus. See attached file for full problem description.

A) By drawing the Bode (with reasonable accuracy at frequencies of interest) and then using a rough sketch of the (full) Nyquist diagram, assess the stability of the following system in a unity gain, negative feedback configuration.

b) What would your conclusion in a (Q4a) have been if the feedback loop has positive instead of negative feedback?

c) Without any calculations, make a rough sketch of the root locus of (see attachment) for positive and negative gain to explain the answer in b and c (You do not need to calculate angels of departure, breakaway points etc. but your sketch must make sense.)