Manoeuvre margin can be selected through Perf Factors (but you need to know the little codeword to effect a change).
CAA requires 1.3g and FAA 1.2g as the limits.
Optimum level gives you about 1.5g (44 degrees AOB) except on short flights when it will give you the level at which you can get to achieve the minimum cruise time which is also specified in the Perf factors (usually 1 min).