Is a cover letter necessary when filing the I 751 petition as long as the evidence is neatly arranged? And who should write it? My US citizen wife on my behalf or myself the conditional resident?I see some very contradicting forums online

Contradicting forums? Always a good idea to include a cover letter. It is from you, the applicant, the person signing the I-751 form.

List off what you are including with the petition; form, check, documents to prove up cohabitation and co-mingling of funds. Make a full copy of the petition for your records and while you are waiting for the biometrics ad the interview, continue to gather supporting documents. Bring copies of the documents to supplement the officers file. The officer usually says something like, "anything else you want to submit ...". Please note, that anything addressed to "Mr & Mrs." or sent to either of you individually, but at the marital address will be useful. Drivers licenses with the same marital address, insurance and your tax return transcripts (check with the IRS website) are particularly useful. They should note your marital status correctly.

I hope this was helpful, good luck.

... thanks cityboy.. by Contradicting meant that some sample letters posted on line showed the US citizen writing a cover on behalf of theapplicant and I found that funny since the instructions don't say that.
Now speaking of evidence how much is too much for the examiner.. :am planning to submit about ten different categories over the two years of our marriage! Is that an overkill or the more the merrier? after submitting the package, what is the wait period?. is it a must to be summoned for another interview to remove conditions on a CPR?
Thanks in advance

Submit all you have, you never know what the officer wants. You will need to check online to see what the current processing time is for the I-751. Most will be called in for an interview, even if you have children, etc.

Good luck.

... thanks city boy !some people were telling me if you have satisfactory evidence , chances are very good for you one to avoid the interview... and also I gather They pick cases at random for quality Assurance purposes... someone was telling me photos are no longer a major requirement how solid is that?

Nothing much you can do regarding interview waiver, so prepare for the interview.

Photo's are always helpful, as most married couples have photos. Include them if you have them and mark on them the approximate date and event. Good if you have photos for the entire time of the marriage. Check your social networking pages as well.

As always thanks for the " counsel " cityboy... will get on the preparation part the soonest... I appreciate the encouragement