I was top 5 earlier today before losing some games.
One thing I think you didn't consider is saving the early 15 gold on rush games, so that you can buy a level 3 card in the first round. In a 4-player game recently, I was able to win through doing that with the 3-card that had 2 rockets on the red side, and the game lasted only 30 rounds. However, in higher player counts this strategy can be countered if players deny you from cards to flip your higher card to the red side.
I also slightly disagree on your point about swap sector cards. The one that can be good is the nine card that lets you swap it for another card with only one charge. That one can be swapped to the 6-slot before swapping again with the 12 slot, allowing you to get a 12-bonus on your 6-slot without too much luck. It does require rolling a 9 and then a 6, but I've won games in 2-player through following that strategy.
Another thing that needs to be considered is the basic breakdown between strategies. These are the main ones I can think of
1) Rush strategy - focus especially on digits 1-6 and then look for rockets. In 4 player games, this is most effective by looking to get rockets on the red side as soon as possible. Save up for colony cards early on (at 10-20 rockets) and try to force the end of the game before anyone else gets something going. This strategy is most effective with higher player counts.
2) Income strategy - look for income cards on the 7 and 8, and focus on maximizing early. Doesn't work in 3-4 player games unless you can flip an income bonus to red early. In the late game, buy colonies to finish out points.
3) Combo strategy - use arrow cards between 7-12 to set up high bonuses on red. This strategy is probably the quickest if set up correctly, but also easily blocked.
4) High-points strategy - use the cards that increase dice to allow you to more often get higher bonuses ranging from 10-12. I think this is too slow as a main strategy, but you can add elements of it if you have a strong card early on.
In any one game, the best strategy will usually use elements of different strategies from those outlined above.