Two questions really. First, can space maranies recover their Drop Pods or are they one use things. I know there are landers large enough to drop landraiders I guess they may be large enough to recover Drop Pods. If Drop Pods are disposible, then does that mean that space marines always need some other transport, like a Thunderhawk, to get them back into space. Since Space Marines are so few in numbers I can imagine recovering troops and material so that they can be quickly re-deployed would be paramount.
Second Question: How does the Empire land and recover Titans. Those things are huge. Does the Imperial Guard / Imperial Navy just have supper huge dropships. Does the Adeptus Mechanicus have their own dropships for Titans. Titans like space marines are such a valuable military resource, I can not imagine that a commander could afford to leave them on a planet any longer than nessisary before redeploying them to the next battlefield.