1) if you want to gain 25 pounds LBM, cardio is a no-no. gain about 35 pounds then cut off the 10 pounds of fat youll probably gain with it.
2) yes, you can do abs more often. 2 times a week is fine, some people even do 3. dont do them every day though, like some would suggest
3) you dont necessarily need to do forearm excercises, unless you arent getting an bigger in the forearms. great excercises for the forearms can be found in the forearm thread in this same forum on this page.
by the way, i would split up day 2, and do more sets per body part. when i train chest, i do 9 sets, tris i do 8 sets, and shoulders i do 10 (i train the heads individually). 13 for all is probably not enough. especially since you have no posterior deltoid work.