Don't forget the ship is cloaked, and its crew consisted solely of droids... so I doubt a couple of exchange thugs will be of much use. But yes, he could use his connections to discover its location. But then again, won't G0-T0 take extra care to hide it?
Very true, but look at KOTOR 2. There are plenty of ways to find the ship. And it decloaks when it picks up new ships. All Plagueis has to do is wait for it.