Halo 4 Forge Race help

I downloaded the game type and i found that hill markers are the checkpoints and user data in advanced starting from zero is the checkpoint counter . The label for the checkpoints is race_flag .

I played in “Racenarok” ( after playing online in matchmaking ) map in custom games but i didnt spawn in a vehicle other than mongoose ( and that was only once ).

I created a test map and i didnt spawn at all in a vehicle .

Question1: is the game type locked only to mongoose ? ANS: No
Question2: the label race_spawn is only to mark the initial/respawn points to make them game specific or does it serve as something else too ?
Question3: the hills in Racenarok had also the label race_spawn . Is it to make the player spawn ahead of the beginning , closer to the next checkpoint he has to pass ? ANS : no
Question4: is the “spawning in a vehicle” online only or maps that are not custom made ? ( maybe that one time i managed to do it , it was by accident , since i cant replicate it ? ) ANS: No

Thank you for your help !

Update : Racenarok works only with mongoose in custom games
Update 2 : in order to spawn in a vehicle , while in forge mode place one of the vehicles ( mongoose , warthog-any , banshee and ghost ) and the game automatically spawns you in the vehicle and the rest do not appear on the map .
Dont know if the label race_spawn is still needed though in the initial spawn / respawn points for it to work. The number of players do not need to equal the number of vehicles ( example : two mongooses on the map are enough for the game to spawn all 8 players in a vehicle )
Update 3 : Q3 : No , the label race_flag must have something to do , not the race_spawn
Update 4 : initial spawn do not need race_spawn to make the game spawn you in a vehicle , but the game still need the label in the map