You can only get Magistrado Ld when his missions are available. I think he just barely left rotation, so it will be a while before you can get him again.
As far as Survivor goes, ELO or T2? For elo, I'd probably go Derby Queen, El Papa Gallo, Fuerza Ciega, Mama Killa, Tengu, and maybe La Salerosa, Wonder Lana and Miss Derby Queen. On GHEIST/Roots weeks you could sub Cage Troy or Rey Mono or even Mr Pollo, if you like.
For T2, Noctezuma Cr, El Divino, Kinichaw Cr, El Gascaro, Lumber Jack are a must. The last 3 slots could be a leader (or not) and any combination of Mama Killa, La Cobra, Tekkuman, Fuerza Ciega and even El Mariachi (if you want to force your opponent to go first).
Survivor ELO: Gatuchica / Derby Queen / Papa Gallo / Tengu / Wonder Lana (Rey Mono if you're having SoA issues) / Mama Killa / Fuerza Ciega or El Matador / Lumber Jack or Tekumman Survivor T2: Noctezuma Cr / Kinichaw Cr / Lumber Jack / El Jaguar / El Divino / El Gascaro / Tekumman / El Matador or Leade