From the way that I read the past few S-1/As, there are two levels to this subscription, Basic and Over. With Basic, you get a 1:1 match at $1.75 per share. If you fill out the basic subscription, there is the Over-subscription. The over-subscription is a 1:"as many as you want until the shares are gone" also at the $1.75 rate.
So, as I read it, you only need 1 share to be eligible for as many shares as you want at $1.75, that is until the 28m shares are sold.
The other way to get in is to invest $1million or more as an outside investor.
Am I missing anything?
I've not found a selling restriction... have you?
As for how much they will invest, that is all up to them.