yes
Yes it is perfectly leagal
The baseline in basketball is the boundary line behind each basket. It is significant because it marks the area where players can go out of bounds. The baseline impacts gameplay by limiting where players can move and making it easier for defenders to trap offensive players. It also plays a role in setting up offensive plays and strategies near the basket.
An NBA size Basketball court is 94 feet from baseline to baseline and 50 feet from sideline to sideline.
Basketball
yes the player is allowed to move so far along the baseline
Baseline so you can trap him there. Middle is the main focus of your defense.
2.857 feet
2 point area
Assuming you mean back and forth from sideline to sideline or baseline to baseline, that would be called a suicide.
it is the big thick line behind the back board
The baseline in basketball is the boundary line running along the width of the court. This line is used to pass in the ball when the opposite teams scores.
NCAA and NBA: 2 courts of 47 feet by 50 feet each w/ 2 inch dividing center line. 94' 2" total length (inside) baseline to baseline High School: 2 courts of 42 feet by 50 feet each w/ 2 inch dividing center line. 84' 2" total length (inside) baseline to baseline. FIBA: 2 courts of 45.93 by 49.21 feet each w/ 2 inch dividing center line. 92.03' total length (inside) baseline to baseline.