Your first hatch...ever?
'Don't count your chickens'.....but get housing ready for them.
Plan to keep them all until POL, just in case.
Will you slaughter and eat the 'extra' males?
Ditto Dat.
That's very hard to say. Selling chicks/chickens is fickle and often a crap shoot.
If you(can) get people to commit, with money, beforehand they won't back out.
But if you don't get the hatch rate you think you will then you will have to reimburse.
If they don't have to put any money on the...