Many things about how exactly you rig a figure are style choices as much as anything.  I think a major one that should be done the same way every time, is that the root bone (typically the Hip) should always be perpendicular to the ground (that is, x and z values for the end points should be the same for each end, and preferably 0/0).  This allows you to rotate the hip along Y and the orientation of the figure will be the same from front to back.  You don't HAVE to do this, but it's a common standard and very helpful for the user, and when the root bone is not perpendicular to the ground, some users get annoyed (I would, for one).

Things like the foot bone pointing to the front or the back, imo that's just preference.  It mainly matters when you draw the bone, Poser will try to guess the joint rotation order that you want to use - sometimes it guesses wrong, or sometimes you will end up moving the bone's endpoints and you'll want to change the rotation order.  This is why you don't bother setting joint parameters or rotation order until you get all the bones placed where you think they should be, because if you change your mind, you have to redo joint parameters.

The two key points to keep in mind when choosing rotation order are: a) the first axis is always TWIST; and b) the last axis is the one that you want to have the majority of bending done with.  For up and down bones (hip, leg, head e.g.), typically this is YZX.  For bones that are perpendicular to the body and stick out to the sides (like the arms) it would by XYZ.  For bones that are perpendicular to the ground and stick out front and back (like a tail) it would by ZYX.  Fool around with it a while and you'll figure it out.

Orientation should be aligned with the polygons of the body part.  After you get the end points where you want them, in the Joint editor window "Center" view, there is an Align button.  This averages all the vertices of the body part's geometry and then aligns the bone to the longest cross section. 

Setting up IK is detailed in the manual and explained a lot better than I could do here, although I will say that doing it inside Poser is pretty cumbersome and fault-prone; I do it with Dimension3D's Poser File Editor, it makes it much easier.

That model of yours is done pretty well, nice job :)

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