How to extend landing gear

KSP includes a "Debug Menu", which you can access with Alt + F12. From within this menu there is an option to disable gravity. Once gravity is off, go to the Kerbal you need to save and use the EVA pack to gently lower them to the ground.

You can read more about the Debug Menu here

You can transmit your science, but this is less than ideal, especially since your station is in Kerbin orbit. For everything except EVA and crew reports, you won't get full value for that science. So, as your thinking goes, you should gather all the available science, and return it to the surface via a kerbal in a command pod.

The way to do this is to send a kerbal out on EVA to collect the science from the instruments. Get close to the experiment, right click on it, and an option should be present to collect the science. You can also do this for command pods that had science stored on them. I would suggest collecting science from the lab first, if possible (I'm unsure exactly how the mechanic works with regards to the lab), and then move on from there. Once all collected, you can then store the data in a command pod using the context menu, enter the pod, detach, deorbit, and recover the vessel.