NEWBIE E-liquid confusion!!!!! 3 different ???'s

I came across this site:
e-liquid|e-liquid nicotine|e-cigarette liquid series
After reading the statement (in green) attached to the 10ml bottle, is this a concentrate or what? The 20ml bottle statement (scroll down) is different?
I am thinking it's not a concentrate but they are assuming 1ml = a 20 pkt of cigs?

Also after going through AV and others, old and new threads, I still don't know the best/cheapest places to go for nic or concentrates!!! 100mg/ml nic is the easiest to calculate (for me, I also know of e-liquid calculators)? EG: ONE SAID: 100% pg stores nic best for longer (in freezer), not quite as stable in 100% vg? Bottle color can also make a difference? What do I choose????

Just one more! I was top of class at maths but dealing with chemicals can be way different! So, I was thinking of adding 2 of my 24mg/ml nic E-liquid flavors together (in little batches to try), then had second thoughts...... Really dumb question, I suppose but I thought of 5 different out comes if I did this:
1 - I get a mix of flavors in 24mg/ml nic? Using equal parts of 1ml each.
2 - I get a mix of flavors in 48mg/ml nic? Using equal parts of 1ml each.
3 - I take 2ml of 1 flavor, 1ml of other flavor and get 36mg/ml nic?
4 - I use a 24mg/ml nic flavor (2ml) and a 18mg/ml flavor (1ml) and a 6mg/ml nic flavor (.5ml) I get a different result again?
5 - I got the whole idea arse up!!!!

Me thinks I think tooo much!!!! :nevreness:
Sometimes there is way tooo much information out there on things so I am asking the experienced out there (sucking up much) :redface-new:
Thanks in advance. :encouragement: