Can I fly for commercial jobs with just my temporary certificate?
A temporary certificate is valid for everything that a permanent one is valid for; it's just, well, temporary.

14 CFR 61.3:


  No person may serve as a required pilot flight crewmember of a civil
  aircraft of the United States, unless that person:
  
  (1) Has in the person's physical possession or readily accessible in
  the aircraft when exercising the privileges of that pilot certificate
  or authorization—
  
  [...]
  
  (iii) A temporary certificate issued under §61.17;


61.17:


  A temporary pilot, flight instructor, or ground instructor certificate
  or rating is issued for up to 120 days, at which time a permanent
  certificate will be issued to a person whom the Administrator finds
  qualified under this part.


(See this question for what happens when the 120 days are up.)

As far as the FAA is concerned, your temporary certificate is no different from a permanent one. I suppose it's possible that an employer might decline to hire you until you get a permanent certificate but I think that's highly unlikely within the US (employers abroad might be a different story). I've seen people pass a CFI checkride and start instructing within a few days, for example.