No. The liver is a power house. Other functions include: it stores carbs, helps regulate blood sugar, amino acids, carbohydrates, and fats; metabolizes many drugs and hormones; produces blood clotting factors and plasma proteins; and makes bile for the digestion of fat. However, you can live with part of your liver removed; the organ will eventually regenerate and recover full function.
Only briefly. During most liver txps the "native" diseased liver is completely removed + the healthy liver replaces it. During the "anhepatic" phase, no liver is attached at all. Since the liver makes so many important proteins that contribute to vital life processes like helping our blood to clot normally, + it is attached to very major structures, keeping this period brief is critical, < 2-3 hrs is optimal.