yes you can change the lawyer at any time. i am neither involved in any law firm nor i am a an immigration expert, but thru my experience i know quiet a bit of knowledge and information. not to offend. AEX, but the fact that you wrote, if your labor cert is done your major hurdle for PR is passed is NOT TRUE. LC is simply to prove that your sponsoring company couldnt find any legar worker so they have to sponsor you, beside that, in I 140, they need to show enough cash flow, asset , to prove that they have financial affidative, wich is filed by the employer in your behalf, thats the most diff hurdle not LC. depending on the visa availability you could also file 140 n 485 concurently, that should reduce the time frame significantly rather than if u were to file separetly, drawback is that, if your 140 is declined your 485 is declined automatically. 765 is for work permit, and 131 is for advance parole = travel document. thx