For a plot event, I'm supposed to talk to Angus Santana at Interplanetary Aid on Anhur. I went to the planet and the transit wouldn't let me go to IA. I thought maybe I had to look up Santana and IA in the database first. So I did that, but still won't let me go there. The destination just doesn't show up on the transit. What am I doing wrong?

Same thing happened to me. I bought the game from GOG and started a new game. I was looking to do the main plot missions, but I reached this dead end.
I read somewhere (after many searches) that I have to restart the game (start a new one). I don't have the patience to start over, this is really sad. I also have old save games from many years ago (when I had the best ship, etc), but the game will crash when I leave any planet, so those saves are wasted too... I really thought this was worth the money, but I guess it was fun then, now it is just frustrating.

Wouldn't GOG require the game's source code to make a 'patch'?

I played the "unofficial patch" Version and didn't encounter the problem. (Payed Hal Taffin and found Interplanetary Aid after that)

It is also mentioned here:
wcnews.com/guides/p2taffin.shtml

Thanks a lot, luckily I had a save game just before meeting Taffin, so I used the other dialogue option (saved credits too) and the went to next mission without issues.

I have just finished the main quest line, I really enjoyed it, but besides that the game is pretty dated and flawed compared to other space sims from that time.

By the time I installed the unofficial patch, it was too late. The event already occurred, and the patch doesn't fix the problem after the Hal Taffin encounter if you've paid him. I really liked the game, mainly because there was more variety in missions then in Privateer 1. The downside is that there are nowhere nearly enough plot missions and there are too many bugs. In addition to the one I already brought up, there were at least three missions I failed because the game wouldn't let me complete them (thankfully none of these were plot missions)

Also the game basically forces you to be a good guy most of the time. Being a black market arms dealer is too much of a hassle and not profitable enough to be worth it. And you don't even have the option to be a pirate (you can't blow up civilian ships and take their cargo). While I liked having the option to hire a cargo ship, I didn't like that it was necessary in order to carry any cargo at all. I should have been able to buy a ship that carries cargo on its own like in the first game.

Also, it was frustrating that commodity prices between planets were not posted anywhere in the game itself, nor could you look at the map while you're on a planet. That made it hard to determine your mission routes and how to maximize profit from cargo sales

I played with the unofficial patch and still got hit by this.

Flawed is an understatement, there is so much bad game design here that it's really confounding it came from some of the same people of the first Privateer.

Why wouldn't GOG apply the patch to the version that they are selling?