Balancing IC S19190E suitability

I need a balancing solution in battery pack. Only balancing is required no other function is need.
http://www.sii-ic.com/en/semicon/da...ve-lithium-ion-battery-protection-ic/s-19190/


1. This IC has two functions, overcharge detection & cell balancing. I dont need overcharge function, so can I leave CO pin open & use its balcing function IC?

2. Battery pack has 20 series cells (2.5V-4.2V each). So can I stack these 20 IC, for on series cell each.
I think we can do it, since each IC runs on individual cells only. But there no application circuit for this in datasheet.

3. What is the max balancing current I can set in each IC.
ICB = VBU / (RCBON + RCB)
Vbu = 4.15V
RCBon = 5ohm
suppose Icb = 100mA
then Rcb = 36.5ohm
Wattage = 100mA * 100mA * 36.5 = 0.365W
Wattage dissipation in IC = 100mA * 100mA * 5 = 0.05W
I think this can work: http://www.digikey.com/product-detail/en/vishay-dale/CRCW251236R5FKEG/541-36.5AFTR-ND/1173543


But what's the max balancing current that can be set so that IC can have its proper operation. Entire balaning current passes through, 5ohm Rdson of the IC.
Figure 7 in datasheet shows power dissipation power? How to calculate max balancing current, so that IC work when PCB is in IP68 box?
What differnce in board 1 & 2 makes as below Figure 7, whether its 2 layer or 4 layer? Since track connections are both on same?