You are correct. If you teleport into combat, you still get the remainder of your actions that round.
There are a few downsides to this, though. The most important is that teleport has a chance of failure. Even if you're teleporting in a very familiar area, you might roll the 00 and wind up elsewhere. Most combats don't happen in a very familiar area, so if you do this often enough you're bound to suffer a mishap.
Greater teleport gets rid of the failure chance, but it's high enough level that it cannot be Quickened. So, since you're using up your standard action to cast the spell, you aren't going to be doing much at the other end anyway.
There are a few downsides to this, though. The most important is that teleport has a chance of failure. Even if you're teleporting in a very familiar area, you might roll the 00 and wind up elsewhere. Most combats don't happen in a very familiar area, so if you do this often enough you're bound to suffer a mishap.
Greater teleport gets rid of the failure chance, but it's high enough level that it cannot be Quickened. So, since you're using up your standard action to cast the spell, you aren't going to be doing much at the other end anyway.