Bobby,
It's best to get info on objectionable chemicals straight from the horse's mouth - the flavor manufacturer (PA, FA, Capella, etc.) rather than from a reseller. If not stated on their web site product page, just email them and ask. PA in particular seems in-tune to vaper's needs and concerns, and prices are great (also good source for bottles and diluting liquids).
Regarding nic liquid, I prefer 100mg/ml PG because I can dilute to any nic strength and also achieve fairly high VG percentages. I buy from from myfreedomsmokes.com, as they have good accountability and have great sale prices. That gets the per milliliter mixed cost down to around 3-cents!
As with any nic base, you just need to be very careful in handling procedures and make sure children and animals cannot gain access to it. I prefer to store mine in the frig in safe packaging and out of easy reach, and take out small quantities only as needed for my mixing bench.
Enjoy your new-found hobby!