Hi, I have couple of questions.

I got my I-140 (application which has stamp of approval) through USCIS Freedom of Information Act and Privacy Act. I do not have the I-140 I797 approval notice . My employer is not willing to share it with me.
1) Can a new employer apply my I-140 based on what i have from USCIS Freedom of Information Act and Privacy Act ?

I have worked as senior software engineer, software engineer and programmer for 10 years now. I have worked on various technologies and programming languages like ruby on rails, php and most recently Go lang (programming language) . I have I-140 as a computer programmer. If i change jobs now and apply for I-140 (new/transfer)
1) will my priority date remain same if i apply as software engineer or senior software engineer ?
2) Does me shifting programming languages matter ? experience letters all say what i worked on over the years.
3) When i apply for new/transfer I-140 does USCIS care about me changing programming languages ?
4) My new employer most likely will not give me Go lang (programming language) experience letter (3 years). Does that matter when applying for new/transfer I-140 ? I am on H1 and paystubs to prove i worked and was paid.