For the first one, there is no way to do that. But, there's almost no point to ever having more than one, possibly two space docks active at a single time, anyway. Sending ships on long treks from way off is a waste of travel time, and having so many docks is a waste of energy in most cases. You can get more ships, faster, with a single or pair of docks and a bunch of engineers (which can be ordered around via the search in the galaxy map if you need to).
For the second one, by design you must deal with captured stuff "where it lies." Thus the incentive to weigh where you care capturing such things, and it creates interesting defensive challenges on those planets at times, too. It won't let you just turtle up!