The only advice i can give about getting the correct media is to purchase it along with your plants from the carnivorous plant grower your buying from.
I do this and it takes away all the problems of trying to find the right stuff in shops as most of the stuff found in shops is problematic as the above posts clearly show.
I was getting so frustrated at not being able to find the correct peat to use that i almost gave up growing these plants-the next time i ordered some vfts through mail order i made a point of getting some peat aswell and trust me it's so much easier on you as you know if the plant starts to decline in health it's not because of it's growing medium.
Soap as a wetting agent-whoa that sounds really bad for vfts lol...i'm so glad i just buy my stuff from the grower lol makes owning vfts so carefree with no hassles over media.
Purchasing your media along with your vft is so much easier in my opinion because you know what the grower uses works.
Also if you find your having problems with finding the right additives for aeration and not completely sure what your buying then my advice would be to keep it simple and just use peat, as peat usually has enough pieces of bark/moss fibers etc to provide sufficient aeration.
Anyway from looking at your plants they look fine and the dieback isnot anything serious as this always happens with mailorder plants-there just acclimatising-as long as the growth points stay green your plants will be fine.
Remember these plants grow in really rough conditions and are very hardy so you shouldn't have any probs growing them as long as your providing them with the right conditions.
I have also noticed that plants purchased in supermarkets etc already in pots do a lot better than plants purchased through the mail from specialised growers-it takes mail order plants quite a while to recover compared to plants purchased in pots.
Nice photographs by the way,hope your plants go well.