I got the Speeder Showdown in the same manner as described....use a ghost character and just fly really slow when your on the speeder. I found that the only way I lost hearts was smashing into the trees you can't shoot...so I just made sure to fly slow in those sections. There really only is one or two sections that is hard to navigate through.....always held the fire button down, the entire time.
I got Falcon Flight in the described manner...fly through and only blow up rocks to get bombs or hearts. I think I got through the level in like 10 minutes. The hardest part is the end, with the big rock, but I just flew in really small circles right by the rock...because there are two small rocks that spawn there...so shoot those to get your purple torpedos.
I have not been able to pass Hoth or DS2 yet...but am excited by two pieces of information I learned through reading this post. One, the rubber band on "x"...and also the "a" button....I was completely unaware that it made you barral role. I'm figuring those two hints will get me through the DS2 level...as well as your ship selection. I tried the Boba Fett ship last night and it did really well in the outside section with the Star Destroyers...behaved very similarly to a ghost ship...I just seemed not to get hit. It was not as useful inside the tubes before you enter the core. I'm going to try the Tie Interceptor as recommended. It seems that there is two ships of choice for the core...the Tie Interceptor of the Millenium Falcon. I think I'll try the Falcon as I hate that ship, but it seems to do well with multiple bogeys. And then it sounds like the Tie Interceptor or Y-fighter is recommended for the exit out of the exploding death star.
On Hoth, the only problem for me is the portion where you have multiple enemy targets. I can shoot down the first wave of drones...and the second wave of 2-leggers....and the first wave of 4-leggers (this section has been problematic though on about 50% of my attempts)...it is just that mixed wave that is causing me problems. Seems, as was posted, that the spawns are most intense on this section of the game. I am anxious to try the strategy that was suggested...take out all drones and 2-leggers first as they do not respawn.
Wish me luck...these are the last 2 achievements for this game