Termination doesn't affect your PR application. You have already been selected by Quebec (CSQ) and federal does your security and medical only.
No need to report, even if you do, they aren't concerned.
Since you asked in other thread about EI - You are entitled to it.
Your A75 also gives you a valid status upto its duration. If you find a different employer, they have to file a new job offer and you a new A75. You can't straight away work for them, have to wait till confirm email on your new A75. Process is fast 10-15 days max.
Hope this helps.
All the best.