Hello Mr. Yash,
CA in Mumbai CAN do an audit of company whose regd office is in Goa. ICAI has issued self regulatory measures but they are in respect of branch audit and joint audit and these measures are voluntary and not mandatory. Hence for audit of company itself, such CA in Mumbai will not face any problem.
In respect of communication with previous auditor, if you refer Clause 8 of Part I of Schedule First to CA Act, it is clearly mentioned that communication with previous auditor IN WRITING is an absolute condition and has to be followed in any audit.
Incoming auditor shall communicate in such a manner that he will have positive evidence of RECEIPT OF SUCH COMMUNICATION BY RETIRING AUDITOR. Hence, telephonic conversation will not be proper.
In respect of an e-mail, that too will not be proper since you will not have a positive evidence that it is received by retiring auditor (since in e-mail, something like delivery report etc. will not come and non receipt of failure notice doesn’t mean that it is received by the intended person).
Hence, you will have to opt for speed post or registered AD.
In respect of decline of previous auditor to NOC, your opinion is correct.
All the aforesaid answers are as per my knowledge, hence kindly rectify me if Im wrong somewhere.