BTP AND Road Rail Fire Vehicle

Police :
I build BTP Police stations, apply to the BTP Police dispatch
All staff are then trained

IRV, I use the -
alternative IRV
I then have these set to their own vehicle class -
BTP IRV

Fire :
I build Fire Stations, apply to the Network Rail dispatch, then rename as Network Rail
Upgrade to Railway Fire, move the fire appliance to a Fire Station
An even number of staff are trained, the rest are either moved for deleted
Rail Fire -
I assume you mean the RRU
I use the Network Rail RRU

Not sure on graphic packs that have been updated. But a number of people have posted individual graphics on the forums here you can download and manually assign