In my grand nerdiness, I will answer some of the questions here.
General Grevous is a cyborg according to some of the books and animated series. He is a biological being (race unnamed) that was crippled in a shuttle crash orchestrated by (surprise) the Emperor working through Count Dooku. The scrolling credits in the beginning of ep3 call him a droid, so there's a contradiction there. droid = robot, cyborg = living being who is mechanically augmented. He's obviously not a droid, since he coughs and you can see living tissue under his exoskeleton. Lucas screwed up his own movie there.
The Tantive IV is Leia's ship at the beginning of ep4. It is captained by captain antilles (no relation to wedge antilles, the rebel pilot who flies in ep4, 5, and 6). Captain Antilles of the Tantive IV takes posession of C-3PO and R2 after the implied memory wipe at the end of ep3. Captain Antilles gets choked by Vader in ep4.
The Tantive IV is the ship you see in ep3 and ep4. Princess Leia's full name is Leia Organa. Jimmy Smits character is Bail Organa. Jimmy Smits is Leia's adoptive father. Leia gets the ship through him. Jimmy Smits is a Senator from Alderaan (like Leia will be in the future). Jimmy Smits dies when alderaan gets torched in ep4.