In my opinion, #1 and # 2 is not recommended, even if they have no visibility or influence. The reasoning is — too often we see lawsuit like this.
#1 – No I do not think independence would be impaired because the committee member is not considered to be a covered member of the audit and have no influence.
#2 – Very high chance yes. The law often consider your spouse as a covered member, and your spouse is working for your client, your spouse is earning $ which translate to having a beneficial influence to alternate the results (to benefit the company, which will benefit her).
#3 – This question depends on rather the specialist is independent from the client, and how influence his opinion will be in the audit.
#4 – I have no experience in this, but my opinion will be — it depends if this material misstatement will lead to the report reader to generate misleading financial decision. Like if this misstatement will be a key factor to determine a future project / contract / funds, etc. If it will… then it will almost always be a qualified / adverse opinion (to protect the auditor).
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I might not be correct.
NY - CPA