Regarding the question of knowing what percentage of total equity your stock grant represents, most companies that are not incredibly early stage will simply not tell you.
Pushing the subject further will make you look like you're nosing around where you shouldn't, often leading to the offer being dropped (this has happened to me).
Not to say it wasn't a not-so-great company to start with, but a dropped offer is a dropped offer.
Yeah, it's crazy. But it's super-common. I always ask how many shares are outstanding, and nobody ever has the information at hand. It's like they said, "We're going to give you 10,000 units of some currency. But we won't tell you whether it's a Zimbabwe dollar (current value: $0.002) or a Euro (current value: $1.38)."
I was lucky that my first job was upfront about what I was getting (%, # options, and outstanding shares). I like to think that I have enough confidence at this point that I would refuse a company that wouldn't tell me what me equity is worth.
Pushing the subject further will make you look like you're nosing around where you shouldn't, often leading to the offer being dropped (this has happened to me).
Not to say it wasn't a not-so-great company to start with, but a dropped offer is a dropped offer.