Dear Rumel vai,
Sorry for late response...
Here is ur ans:
1. no its not mandatory.. If u have min 67 point without ur adaptability then no need of that
2. I dont think u need to send those with ur application... u can send this if they make any query for those..Other wise this is an unnecessary doc.
3. I will suggest u to take another copy with another person of that company's ex employee if possible. But if not then:
"Reference letters in the required format are necessary, please try your best to get them. If after all efforts you are unable to obtain a work reference letter, then you should provide a solemn declaration / affidavit explaining in detail why are you unable to do so. The officers at the VO are aware of the fact that different employers have different policies towards issuing such adhoc letters and may not cooperate in issuing such a letter. Please do attach all your employment records with the declaration. I was unable to obtain a work reference letter from one of my employers and did the same. However please bear in mind that the final decision rests with the visa officer handling your case."
4. BC is required with ur application but PCC can be sent on the later stage..so need not delay for ur PCC (but if its ready/can be ready) then send it with ur app..
i hope this will assist u...