Are you trying to start the quest? As far as I recall, that's the only part of the quest that involves Grubfoot. Make sure you have all the prerequisites taken care of.
Not sure if there's still an Excel list, but Tip.it has a feature that does that now. You can check it out here: http://www.tip.it/runescape/index.php?rs2item&stats=true
I would send a bug report because I doubt this was the intention. I did send one, and i hope it gets fixed soon. Doubt it. It's been like that since the quest came out last year.
You could try camping at one monster for a while, and then when you get tired of it switch to another monster. Repeat until you have your desired cash amount.
Your calculations look correct. I've heard the ratio of summoning exp to slayer exp is about 0.8/1, but don't quote me on that. And yes, you do get exp for damage your familiar does. You will get exp in attack, strength, defense, controlled, ranged, or magic depending on which familiar you use.
tears only works for levels above 30. On topic, just buy some planks and make chairs and such till 10, shouldn't cost much. They still work. You just don't get as much exp if your lowest skill is under 30.