有關聲明書之疑問

請問各位專家有關美國申請專利聲明書之疑問：
1.可以不使用代理人提供的聲明書 而用官方聲明書表格嘛？
2.是否也要附上敝事務所之聲明書或委任狀？
3.代理人來函說：
"Rule is that the declaration must be completed before the inventor(s) sign and the application as going to be filed has been read and understand by the inventor(s) before signing."
是什麼意思？？