dimension + expression = 15 maximum upto 15 field you can add but your linkage should be fine otherwise it gives you error object out of memory and allocated memory exceed
for alternate color write this code either in dimension or expresion side click on + icon you cee the background color write this code
There is no such documented limitation i believe. All you have to be careful of is, the performance, because the more the number of columns in pivot table more the performance (front end) degrades, i.e, your pivot may take long time to open.
