For set ylim use ylim=(low_value, high_value) keyword in mpf.plot() or mpf.make_addplot()
For set yticks use next sample of code:

fig, axlist = mpf.plot(**foo_kwargs, returnfig=True)

axlist[target_panel_index].set_yticks(np.arange(low_value, high_value, step))

Note 0.
In my case I have three panels (0 - candelsticks, 1 - volumes, 2 - custom indicator), but for custom indicator I should be set target_panel_index = 4. Why? I don't understand.
Note 1.
And for help: all keywords mpf.plot() and, perhaps, mpf.make_addplot()