As mentioned before, you seem to have access to the wrong kinds of 'information' sources. And the mentioned convoy was clearly a humanitarian one. I had a look into the cargo protocols - the one that were shown to you obviously must have been forged, as it is often the case during rebel missions. Your so-called leaders are conducting a careful desinformation campaign for the average gunman/pilot in order to maintain your morale. Let's be realistic: A pitiful strikeforce of rebels and other criminals would have had no chance against a regular military convoy.
Kachirho City? Ah yes - I've heard of it. It's all fake - a tourist attraction built by some crazed businessmen who thought they could lure visitors to that place by showing them the original and pittoresque Wookie culture. Of course, the plan failed miserably after most of the tourist were eaten. But yes, there are actually still Wookies nesting there. If you've never been attacked by a Wookie, you are a lucky man indeed. Or perhaps you were shown some carefully drugged specimens. I don't know what kind of devices your rebel leaders have constructed to keep them at least somewhat tractable. Perhaps some cybernetic implants in the brain region?
Whatever - once again to the topic of imperial Ties. You seem to think they are simple to handle - that is deceiving. They do have a very clever interface that allows smooth operation ... but trust me: mastering the vessels in order to experience their full power is something else. And I doubt that your simulator models are capable of that. See, even you are forced to admit that the advanced tie models are superior to rebel craft - rebel engineers just can't keep up with their poorly understood stolen prototypes. Anyway, let me assure you: even the regular ties are formidable vessels indeed. If you are wondering why nowadays you are seeing more imperial fighters than rebel ones - well, I can solve this riddle for you: Its because your's is a lost cause. Even the swarms of new conscripts from backwater planet find it increasingly difficult to counter the huge losses your forces are experiencing whenever they meet a proper imperial fleet in a regular battle. It is not to late to repent! Your leaders will only waste you as further cannon fodder! Now is the time to wake up and cross their sinister plans! Go to the nearest imperial facility immediately and surrender. The people there can and will help you.
Glory to the Empire!