I followed the advice of others on the Budget Board. I would never have figured this out myself! But to answer your questions:
*You can find out more information from this Budget Board thread:
https://www.disboards.com/threads/i-missed-the-sw-60k-offer.3615171/ and this article
https://thepointsguy.com/2015/09/how-to-earn-the-southwest-companion-pass-for-almost-two-years/
*There are 3 SW cards; Business, Premier, and Plus. You can find out about them (they may have different sign-up bonuses, minimum spend requirements, anniversary bonus points, and annual fees). One person can apply for 2 (or maybe 3--not sure about that because I didn't need to do it). Some people trade off getting the companion pass by having one spouse get it for X amount of time and then the other applies at the end of that time to keep it going.
*We got both cards at the same time; that is, I applied and was approved for one and then turned around and got the second. I just did it online.
*The pass is a benefit of any of the SW cards, and since the bonus points go into the Rapid Rewards account of the cardholder, there is no need to transfer anything (but maybe I will double check that on the Budget thread). **NOTE: both cards must be issued to the same cardholder!! You can't combine points between different member's accounts!
*Check the current amount of sign-up bonus points; sometimes you can get a better bonus by going through an older link.
*I just checked and currently, you can still get the 60,000 pt bonus with the Business card
https://creditcards.chase.com/a1/southwest/60KPremierBiz?CELL=637V but the Premier and Plus cards are offering 40,000 right now. That puts you 10,000 pts short (actually, 6,000 because your required $2000 spend per card counts too) if you apply for a Business and one of the other cards. I'm sure the sign-up bonus will go up to 50,000 at some point, but the longer you wait, the less time you will have the CP so you have to weight it out that way. The deal I got was so good because I didn't have to spend anything to get the CP points, but you can be creative about reaching the spend. Lots of people pay everything--taxes, groceries, gas, utilities, car--with the card. I've earned quite a bit going through the SW shopping portal for purchases and for booking hotel rooms through SW (sometimes very large bonuses for that).