It is supposed to have a single-player campaign called Squadron 42 (Actually, it is supposed to have a trilogy, with each chapter been a game by itself, with several missions, branches, stories, mocup scenes played by Hollywood actors like the incredible - as recently revealed to the world - ex-Pornhub star Sandi Gardiner, ok ok, there is GAry Oldman too, but he was paid less than Sandi, the wife of Roberts, so, I guess her role is more important)

They claim to be releasing the first chapter by the end of this year. Unless it be an alpha, or broken as hell, or incomplete, or a pathetic set of missions, not a chance. Possibly by the end of 2017 (if the first chapter is to be considered ground-breaking, finished, good, etc.). Giving the status of the gameplay, end of 2017 is very optimistic.
As the game as a whole (including the MMO part) only will become ready by 2022 or later (buy an Idris JPEG to help), once again, if they want to release something legit that be in the level of the hype and promises made, you shouldn't be worried by what system you will need. No investiment now to play Star Citizen would be wise.
If you want to buy into it, go to
https://robertsspaceindustries.com/pledge
You can choose a game starter package and then the access for Squadron 42 (which you have to spend additional dollars for). Then, you can put more JPEG's of ships, or current pre-pre-pre-alpha ships in the top of your package to play with them in their pre-pre-pre-alpha module. I think that the basic pkg + SQ42 is around 60 dollars.
And you will regret. It's going to be the worst possible investiment that you would do with 60 dollars, and as more money these devs get, less game people gets, while waiting for longer.
There is 99% of chances that many of the promised features of this game will never see the light of the day. And it's 100% certain that the devs lie all the time for money, as have been proven tireless.
Good luck. You can make whatever you want your money, certainly, but that does not change the fact that spend on Star Citizen is something that is very fool to do, even if you are a big supporter and want it succeed. If you want SC succeed, don't give them any dime. And if you care with your money, wait for the release. They always let people play from time to time for free anyway. Desperate to try to catch new victims, hoping to transform one or two in whales, that is all that they need to keep the show and their pockets full of money for whatever personal objective they have. The project, the company's future is basically doomed.
That's my advice. Good luck with whatever decision you make.