That I can do
Once healed, no positions should cause you any issues with either of those.
checkout
FlexClass is a specific use case chip, so unless you have a need for it, rule it out.
FlexSecure is an untethered Apex Flex (load your own applets, rather than through Fidesmo, and control your own key)
“a good spot” depends on how you want to use it.
Back of the hand P#2-4/5 is pretty good for most things.
If you dont see yourself using it for locks/access, you could do above wrist (watch area)
ok, the next two…
xEM, could go anywhere really, But, to save real-estate, I would reccomend putting it alongside (>5mm) your xSIID.
If you want it to Blinky 
, i would suggest the forearm would not be as good as the hand, due to the hand skin being thinner.
So Both in ~ P#4 would be doable, personally I like the back of the hand for flex, and P#0 for xSeries But I also have xSeries in P4-L and will be putting xEM next to FlexDF2 in P4-R.
Just make sure you plan ahead, and consider what you may want in the future.
I have a Spark in my Left and xNT in my Right, I really like it, and im not sure why more people dont do it. 
I have prominent vascular hands, and zero issue with either of mine.
I hope that was of some use, but all just my opinion, others my have better suggestions.
Keep us in the loop as to what you decide, and ask away if you have nore questions