All military ships/stations require maintenance eventually, you can make station that has long deployment time and large supply of MSP to have longer time bofore overhaul and rest for the crew is necessary.
...
Are there a special way to make stations or are they simply ships with no engine?
"Station" is just a convenient term for ships with no engines.
You can use the "No Armor" checkbox to make an armorless station, which saves a good bit of cost (and weight) and can be built by construction factories, but may not use any military components.
Yes and no. You can build all components of a Ship without Engine with construction factories and then assemble the station in orbit through shipyard. So I guess the biggest difference between a station and a ship is that Station can be build entirely by Construction Factories while ships or ships without engines must be built or assembled by Shipyards. Also the other big difference which has been said before is that a station will only have commercial components while station ship without engines can have both.
Bottom line:
to build a station in Aurora terms you have to flag the option in the design "No Armor" - only commercial
to build a ship any design over 500 tons and without the flag "no armor" will be classified as ship - either commercial or military
to build a fighter any design equal or under 500 tons and without the flag "no armor" will be classified as fighter
I do agree with Skoormit though that a station could be a ship without engines just remember to have a shipyard large enough to either build or assemble them.
Here Aurora Station rules
http://aurora2.pentarch.org/index.php?topic=8495.msg106780#msg106780