I would say that a 195JJ would be a better suit for some one who is 188cm tall themselves. AKJJs are actually a little smaller than 195, I think with a straight tape they measure 193cm. Also due to the rocker they ski a lot shorter, so I think a 195 AKJJ would be a good suit.
With regards to the binding question, either would suit, provided both you and your father ride on your reccomended DIN setting. I just used my DIN chart and if your both level 3 skiers, your reccomened is 8.5 and your father's is 9.5. As far as I am aware both the STH12 and STH14 are identical bindings apart from the spring, (someone do correct me if I'm wrong here). So you would gain anything durabilitywise from going up to an STH14. I would reccomend getting the 14 if either you or your father are going to be progressing on these skis, because with the 14, you've got 2 settings higher to progress onto if you need.
Mounting point is very much personal preference, however that being said, if you're unsure, I'd just go reccomended to start of with. The JJs are designed with 'backcountry freestyle' in mind, so unless you're planning on landing/skiing pow switch a lot of the time, and I mean a lot of the time, then reccomended should be just right.
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Joey -Formerly *III.JVD.III*
I post from mobile the majority of the time, so if the above is incomprehensible, I apologize.