Yeah that’s the popular nade build now, it takes some dedication to only play with grenades though haha and not use your gun much/at all.
Where do you end up putting the extra 3 points running forge/SF? I guess it’s either Scrappy or AI.
Yeah it doesn’t really matter. Scrappy, maybe one in WCIC, 1 in FitSD.
IB fires the target softening rockets. That’s slag. It’s purple and leaves puddles. I’m calling it slag because it’s a status effect, and it seems to count toward the bonus. 
I put one in FITSD and two in Armored Infantry. That little bit of extra gun damage goes a long way, and having the point in skag lets me use CH weapons more effectively if I need to.
wait does it actually?
I’d need to test it properly, but it seems so.
I’d wager It’s Piss would also get the bonus.
Otherwise the wording would be Damage over Time rather than status effects