Light: depends where you are, "7b" is local idiom, I don't know where that leads…
At about 45° of north latitude, it's facing south or west, with full sun (and with humidity accordingly, not more than 35°C). In a GH, near the top.
For Florida or equivalent, it'd be half shade.
Potting medium: I'm having a great time with a mix of coco husks, bark, perlite, leca, sphagnum. I'm checking some variations with hemp. It should be terrestrial, wet, but able to dry up (if cold), plenty to decay. Never threat them as epiphyte, you'd have horror stories for kids to tell afterwards.
Vanilla are almost all hemi-epiphytes, but grow the best treated a terrestrials.
Propagation:
Cut bits, the longer the better, at least 3 knots. You can let the extremities dry up to a few day (I don't), and plant in sphagnum or mix. I use water bottles with leca 3-4 cm then sphag or mix, I plant 2 knots, and keep moist and hot. I close with the bottle top.
I'm currently writing a vanilla how-to, expect it by this autumn.
Vanilla planifolia 'variegata'
I've already given hints and bits in threads here, but if you have a specific question, just ask 
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