Samar-class escort carrier, named for the Battle of Samar, part of the larger Battle of Leyte Gulf in WWII. The Battle of Samar finished the Imperial Japanese Navy as an effective fighting force, and is notable for many acts of extraordinary courage under fire by the outgunned US naval task force that fought in it.
Not strictly needed (torpedoes being steerable), but I can see a use for them in certain specific cases, and it's a way to put more tubes on a ship w/o 'crowding' them too much.
Not really. Given the layout, the impulse drive is likely fed directly off the warp core in normal operations with fusion engines as backup.