Base Stat Update

I was hoping to get some input about the recently changed base stats for the champions. I had made my own excel file with all the champs stats from the website. http://gameinfo.na.leagueoflegends.com/en/game-info/champions/. I realize there's probably some app or other website with all this info, but I like to have my own sheet to work with as it gives me the numbers at a glance and champion matchups, plus the math is 'sometimes' interesting. So, before it was a simple calculation of taking the champions base stat 'x' and adding champion level 'y' multiplied by their per level stat 'z'. x + y * z

Now there is a whole 'growth statistic' that to my understanding is added each level plus the previous levels addition to the base. According to the patch notes, it works as follows "Gain +((Level*3.5 - 7) + 72)% of your growth statistic." This stumped me on what to do if you wanted to look up a specific level as you couldn't just plug in a level into the above formula without iterating each level before it as well. I came across a formula on the wiki that seemed to work. (http://leagueoflegends.wikia.com/wiki/V4.20) (just after the graph)

So I plugged in the formula and it seemed to work, I was no longer getting abnormally low numbers. Just to make sure if anyone wants follow what I did, I'll use Aatrox as an example, assuming the champion info is still accurate. This is how the formula looked in excel, where 'Base' is base stat provided by champion page multiplied by 1.68, 'Per' is the per level stat gain, and 'X' is champion level. =Base+(Per(((7/400)(X^2))+((267/400)*X)-(137/200))) His pre-patch health was 395 and would gain 85 per level. At level 18, this would mean he had 1925 health. Post-patch his health would be multiplied by 1.68 for a base of 663.6 and a gain per level of still 85. At level 18 using the formula from the wiki, his health would be 2109.

I don't know why but this seems to work. Can anyone else confirm and if possible explain why the formula works? I'd like to know how they got those ratios, and I would like to know if I can trust the numbers before I go overwriting a bunch of stuff.

PS: Also the patch said all stats except attack speed had their stats raised by 168% does this include armor and magic resist? PSS: If anyone knows how attack speed items work that would be useful info as well. Like does it work solely off the Base stat (say 0.651) or is it the current base stat, say at level 10 he had 1.0 attack speed is each per level upgrade considered "Bonus attack speed." So if at 1.000 attack speed without any items and I buy +40% attack speed, what will be final attack speed, 1.400 or 1.2604? Sorry for the length, if you stuck with me you deserve a cookie ;)