Changing from HDD to SSD with my Airport Time Capsule I will receive a new SSD very soon (Samsung 850 EVO 500gb).
My question is, will it be possible to transfer all my data from my HDD(I have a time machine backup of my computer on the airport time capsule).

Like lets say, i a) I insert my new ssd in the mac with absolutely nothing on and unplug the hdd. b) Booting my mac while holding (⌘-R or alt button???).

After that would it be possible to choose my network and choose the airport time capsule where i saved my time machine backup? Hope my question makes sense. Thanks!
As long as you're on your Wi-Fi network, you should be able to do that, but if I were you I'd just buy a SATA-to-USB cable ($30 at Best Buy), install the SSD as usual, connect the HDD over USB, make a disk image of it with Disk Utility (in Recovery), and then install the image on the new drive. I did this when I upgraded my MacBook Pro to an SSD and haven't had any problems with it.