As to the ALPA's legal help after an incident, we at Atlas have first hand knowledge after the DUS incident which later turned out to be the fault of the airport for reporting incorrect braking action reports. They ended up buying the A/C.
The captain called ALPA legal at the airport after the incident and then got a 15 minute dissertation on what ALPA legal lawyer couldn't do and no advice. Not particularly helpfull at all. Luckily the captain was ex FAA and initiated getting the evidence with the local CAA that resulted in the finding of the airport being at fault for the incorrect braking action reports.
ALPA legal might be helpfull in the US, but internationally they suck.
As to the Teamsters, the local has a lawyer on staff who also has access to other lawyers in specific disciplines when needed.