depepnding on the leather.....it does make a difference in the type of needles, feet and thread you should use.
so far i have used suedes, pigskin, pebbled leather, thick goatskin, and thin lambskin .
for suedes, you really can just use a regular sewing machine needle....and regular all purpose thread.
pigskin, depending on the thickness, you may need leather needles.... and sometimes topstitching thread works better than regular if it is really thick or stiff.
pebbled leather, use leather needles, a large stitch and topstitching thread.
goatskin is the same as pebbled leather if it is really thick, and for lambskin i used regular size needles and all purpose thread (not topstitching)
i am not sure about the teflon foot, but it would probably be better than a regular one. especially with the lambskin as it stretches A LOT! i used an all purpose craft glue called Fabri-tac to glue the pieces together about 1/8 in from the edge and then my seams were about 1/4". it's nice because it bonds the pieces together to hold while you sew, but if you mess up, it peels off almost like a rubber cement. it is clear and dries clear and fast like a super glue. this helped me to keep the lambskin from slipping and strestching when i was piecing it all together.
for the most part i would say it is trial and error and always mess around on a scrap first to adjust your tension and see how the thread and needle size affect the stitch and strength of the stitch, since each hide is different and sometimes certain colors affect the maluability of the hide. best of luck!!