Welcome, and what a wonderful set of questions!
„available“ - a ship on general release able to be pledged on at any time.
„limited“ - a ship or variant of a ship that is available or concept, but only able to be pledged on during certain times of the year. for instance the Aurora LN is "Available" release all the time but the Aurora LX is "Limited" release during special sales and events.
Bonus word "Sale" - This is when limited ships become available. This is not a discount sale, don't expect any discounts no SC sales have discounts. You only get a discount with the Subscriber 10% or Subscriber 20% voucher which you get for subscribing to a certain level for 12 months.
„concept“ - this is when a new ship is announced but have not been worked on or is finished. This is the true meaning of the word 'concept' and by pledging at concept stage you get perks like "Life Time Insurace" and a cheaper pledge price but you accept that the ship may not arrive in game as exactly the concept you first pledged on. Things may change, the Drake Herald, for example, was originally asymmetrical and arrived in game symmetrical.
Bonus word "Life Time Insurance" - This is a perk with concept ships, some special availability ships like the Emerald version of the RSI Phoenix, and any pledge ship or pledge package over $1000. No one knows exactly what it is as it will be finalised in the finished game, but at the moment it has been said to be unlimted free hull insurance so you can crash your Aurora all day long and get a new one for free, whereas a normal ship without LTI will have a small fee to insure it to make sure you get a new one when you crash it.
„in production“ - this is when a ship is in "the pipe line" and is being actively worked on. This is no guarantee that the ship will arrive soon though, some ships have been in the pipeline for years and some ships have been waiting for years to get in the pipeline. Don't be angry when a ship comes out of nowhere flyable and fully produced while you have been waiting since 2015 for your MISC Endeavor. Some ships can't be worked on until the tech has been made to allow such things as ship docking and movable physics grids.
„referral“ - The referral system is a incentive mechanism to help you get perks while getting more people into SC. It starts with a couple of free guns for your ship for getting one extra person to join, but goes all the way up to the Javelin which is supposed to be the biggest player owned ship in the game... but you need to get 2017 people to join for that. A little more realistic is a Gladilus for getting 10 people to join :)
Roberts Space Industries is the official go-to website for all news about Star Citizen and Squadron 42. It also hosts the online store for game items and merch, as well as all the community tools used by our fans.
robertsspaceindustries.com
„concierge“ - This is a thank-you to people who have contributed over $1000 to game development. There is a private forum area and a few perks like a top-hat and monocle, a golden gun. You also get a dedicated Customer Service channel which in theory gets your questions answered sooner. There are more rewards as you contribute more and more, however it is not really an incentive system, more a genuine thanks for being so committed to the project.
The Concierge (also known as the Chairman's Club) status is assigned to backers with purchases equal to or exceeds $1,000 USD. The primary benefit of this status...
starcitizen.tools
Hope helps, please don't hesitete to ask any questions that come to mind :).