Let me answer the second question first: It has no impact on rank. The benefit of a complete listing is that you provide more information that Google thinks the reader is looking for. It may, in marginal cases, add to the relevancy of your record on certain searches. That being said, it is not much harder to make a listing 100% complete than 80 or 90% complete and there is no harm in it.
At the Webmaster-Zentrale blog in Germany, they have recently tabulated a guide to one possible way to achieve a grade of 100%. There are several as I have achieved 100% with only 2 videos. I have translated and plotted their results here.
If you compare this chart to a similar % complete chart that was done last year, you will see that the value of basic information has increased somewhat. There are minor adjustments, both up and down, elsewhere. An interesting aberration that showed up was that by adding the first video, the % complete actually dropped by 4%. This effect has been confirmed by EHG, one of the Top Contributors in the Places Help Forums.
|Required Fields, Company/Organization, Street Address, City/Town, State, ZIP, Main phone||53%|
|1. Additional Detail||1%|
|2. Additional Detail||1%|
|3. Additional Detail||1%|
|4. Additional Detail||1%|
|5. Additional Detail||1%|