Should be the same training as any other driving job as you'll be on Network Rail metals from Pelaw Junction onwards. Of course the training will be slightly different to take into account the specific rules and regs for the Metro-only sections.
Wage is circa £32k, half of that for the training period. You'll also have the added benefits of free travel on all DB/Arriva Trains UK services (Grand Central, ATW, Chiltern, CrossCountry, LOROL), along with free travel in Tyne and Wear on all public transport, Priv discounts on Northern and TPE. Add to that the Local Government Pension Scheme.
The tests are indeed down at Doncaster, so should be exactly the same as the ones mentioned in previous topics in this section.