The vaccuum of space doesn't get in his wiring.
Luke doesn't know Yoda. It seems better to use Obi Wan as a reference - and remember, Yoda still would have wanted to test him. If he invited Luke himself, then he wouldn't have been able to do that so well.
Maybe they couldn't find anyone. But the probes seemed to find the base quick enough. They tried torture in the first movie and it didn't work. It took the entire movie to find the rebel base. The probes found it about ten minutes into the film.
You have to remember the Mellenium Falcon was travelling at sublight speed. It would take ages to get there. So Boba Fett is hanging back, watching this thing slugging its way to a small sphere in the distance. And he undoubtedly thinks "I guess this planet is where they're headed." and it's safe bet as it would take years to go to another planet. So he calls Vader and they all get there by lightspeed and have time for several rounds of charades, while they wait for Han to arrive.
And they did. I also distinctly remember Darth Vader asking Admiral Piett if his men deactivated the hyperdrive on the Mellenium Falcon. And I remember R2 telling Threepio that the city central computer told him the hyperdrive had been deactivated. Threepio didn't believe him.
Lando's men fixed it. Vader's boys de-activated it - so it seemed like it wasn't fixed. R2 re-activated it. Why are so many of you shady on the details when it comes to this point? It was all pretty explicit in the movie.
Lack of retribution? They stole Lando's city from him and took over the place for themselves, no doubt putting up an Imperial garrison. Seems like pretty heavy retribution to me. No need to blow it up.
Also, it was a great resource. Alderaan, since you mentioned it, may have been a great resource - but it was even better demonstration to all the people in the galaxy about why no-one should mess with the Empire. Remember, Tarkin said Dantooine was too remote to make an effective demonstration? So, I would think that a small mining colony no-one's ever heard of would be even less effective.
No, may as well make some money out of it.
However, I know what you were trying to do. You weren't saying that The Empire Strikes Back was a bad movie. You were saying that if you didn't like the movie and wanted to look for things to pick on, you could find them.
It's a good point - except that there's not much available for criticism.
I pick on Return of the Jedi for an uninteresting, simple resolution of potentially very exciting plot threads. I pick on it for retreading old ideas, simplifying the characters, being terribly inconsistent with the other movies and within itself and its excessive use of Ewoks (ie. having more than zero ewoks in the movie). So it's got lots more to pick on.
The Empire Strikes Back however, leaves the person who wants to pick on it with very little. It is fresh, original and it expands the scope of the story considerably. The characterisation and the journeys the characters go through are very involved and moving. It flows on very nicely from where Star Wars left off and it has, and I am absolutely certain of this, no ewoks.
And this is the difficulty for those trying to pick on it (unless you're George Lucas of course, who hates characterisation and interesting stories).