From the Commissioner's office...
Pre-Draft rosters must be reported by March 8. You can do so before then, but all cuts become official on March 8.
At that time, the Draft Grid will be adjusted to fit the number of players you protect.
With a couple of exceptions*, teams may protect as many players as they want (30 max). Teams are all limited to 30-man rosters, post-draft, all of whom must be carded. You are allowed an additional roster spot for each Reserve pick you own. Players kept on reserve may be carded or uncarded.
Remember, you cannot protect, draft, or keep an uncarded player unless you have a Reserve to cover it.
*Per the demerit system, the Nads are limited to a maximum of 18 players pre-Draft. The Wahoos are limited to a maximum of 16 pre-Draft players.