Thanks for playing at Fleaflicker.
1) Your league is a weekly lineup. So once that player's team (who is in the slot) plays their first game of the week, the slot will lock and the player is there for the remainder of the week until scores finalize.
2) You can pick up players at any time, but they will get placed on your roster for the next week if all slots have been locked for the current week.
3) Forwards are any C/RW/LW