Can 2 CT scans, 4 us during last 4 years picked up liver cancer? Ruq pain since 2007 and no diagnosis yet, would I be dead by now if it was cancer in 08?

Yes and maybe. Ct and us are both sensitive at detecting cancer. If they haven't seen it on the 6 combined studies it is unlikely to be a problem and is certainly not causing discomfort since any cancer large enough to produce that would certainly be visible. If you had primary or even worse - metastatic - liver ca in 2008 it is very likely you would have passed by now.
Probably not cancer. 5 years of pain unlikely to be cancer, and certainly a liver tumor would grow enough in 4-5 years to show up on imaging studies. If you have been having unexplained pain for 5 years and nothing shows on ct or us, you may need endoscopy and/or nuclear studies to look at other possibilities (gallbladder, pancreas, bile ducts, intestines, etc.) - consult with a GI doc if you haven't done so already.
Not necessarily. If the liver cancer were small, it might not be visible, but statistically speaking, if it were liver cancer and was first detected in 2008, your survival chances 4 years later, depending on the type of tumor, would be poor.