I was looking through the various space stations. There are many designs and several of them are self explanatory.

Ship Yards: The bigger the station, the bigger ship you can build
Recycling: lets you scrap space debris
R&D: Currently useless but will presumably assist in research when the option opens up.
Defense: Golans and Ataturk-Class. These have relatively high weapon and defense ratings so I am guessing their only function is to detect and shoot enemies.

What is the purpose of the other stations? There is a wide range of weapons, defenses, and cargo space. Asteroid hideouts, Trade 1, Platform XQ1, Merchant Space Docks, and a few others. If their only use is to hold cargo, it seems more efficient just to use ships which can move around. Do these stations earn the owners money like several planet facilities do? If so, is there any stations that an individual could use as an investment or are they only useful to a faction?

The page on faction creation shows what factions can build which stations - http://www.swcombine.com/rules/?Faction_Creation

The page on Space Stations gives a general comparison of weapons, defenses, and cargo space - http://www.swcombine.com/rules/?Space_Stations

Neither of these pages gives any in-game information on exactly what the stations DO. For example, How big of a ship yard is needed to build a given ship and can a trade station earn credits on it's own? I know these questions have to already be answered but I couldn't any station threads in the question center. What other pages can I look at to find these answers?

For ship size and ship yards:
1.1/ What is Production « Back To Top
Production is the creation of ships, vehicles, items, weapons and droids in facilities and space stations. All ships may be built in shipyard space stations (see Space Stations Rules) if the ship is the length of the station or smaller (doesn't apply to stations 3km or larger). Factories and factory stations are limited to ships less than 80metres in length. All Boats and Submarines are produced in Naval Shipyard facilities. All medical items are produced in Labs or Medical Factory Stations. All other ships, vehicles, items, weapons and droids are produced in factories or factory stations.

Directly from the rules

The rest are mainly RP ish places to have a home, especially the space colonies. The Asteroid Hideout is exactly that - it is the only buildable station that has an ECM value (and pretty high one at that) allowing you to hide in a system or wherever.

Asteroid Hideout - Nice for hiding things, as you need a lot of sensors to see it
Ataturk Station - The poor man's Golan, smaller storage and weapons
Golan 1 - Weapon Defense Platform
Golan II - Bigger Weapon Defense Platform
Hospital Platform XQ2 - Hospital Station, just like a Hospital Facility
Luxury Space Colony - Think a mansion in space. Best of the publicly available station DCs to build.
Medical Factory Station - Works like Lab facilities, can produce medical items
Merchant Space Dock - Used as faction HQs
Platform XQ1 - Used for fighter storage around planets
R&D I - Small R&D Projects
R&D II - Medium R&D Projects
R&D III - Large R&D Projects
R&D IV - Massive R&D Projects
Recycling I - Small Recycling
Recycling II - Medium Recycling
Recycling III - Large Recycling
Recycling IV - massive Recycling
Shipyard I - Small Ship production
Shipyard II - medium Ship Production
Shipyard III - Large Ship production
Shipyard IV - All Ship Production
Space Colony 1 - Cheapest station, good for starting player who wants a deep space base
Space Colony II - Upgrade to Space Colony 1, slightly better deep space Base
Trading I - Good storage for factions, allows NPC Market Access
Trading II - Better Storage for factions, NPC Market Access
X7 Factory Station - Works like factory facility, can produce items/droids/vehicle/ships

These Stations are unique Stations owned by the Admins and will possibly have some minor quests tied to them at some point.
Abek's Station
Centrepoint Station
Galactic Museum
Jubilee Wheel
Junkfort Station
Khiluum Station
Koda Station
Maw Research Station
Petabys Station
Starforge Station
Tranquilla Beach
Tansarii point
The Wheel
Void Station

Answer Enough?

Trading I - Good storage for factions, allows NPC Market Access
Trading II - Better Storage for factions, NPC Market Access
- access to NPC market is only provided if the station is owned by a Trading faction and open to all

There are of course necessary requirements, I was just listing their general purposes.

Yes, this answers my questions perfectly! I was originally considering whether space stations could be a direct profit bearing investment like some planet facilities. The answer is no. But now I have a much better idea of what each station is intended for and capable of. And I didn't know that There were unique stations around. If they ever do get quests tied to them, I will have to start exploring more!

But that makes me curious about deep space exploration. It would be interesting to set up a space-colony station in a small piece of space that nobody knows or cares about.

But that is a lot more research for another time. Thanks again for the answers!