1. Does XPO provide any existing designs or some formats for reference or quick start?
Check out this article for different ad templates. The XPO platform also comes pre-loaded with many ready-templates for you to easily get started.
2. Does XPO support iAB Rising Star AdUnits ?
Yes, XPO supports iAB Rising Star Ad Units (http://www.iab.com/guidelines/rising-stars-ad-units/) for both Display (http://www.iab.com/guidelines/display-rising-stars-ad-units/) and Mobile (http://www.iab.com/guidelines/mobile-rising-stars-ad-units/).
3. Is XPO ad format certified for use in Google ADX/GDN(Google Display Network)?
Yes, XPO-generated ad tag is certified to run on Google ADX/GDN as global third-party ad vendor (https://support.google.com/3pascertification/table/4570113 and https://support.google.com/3pascertification/table/3191570?hl=en&ref_topic=3191569).
4. Is XPO expandable ad format certified for use in Google ADX/GDN?
Yes, XPO-generated expandable ad tag is certified to run on Google ADX/GDN as global third-party ad vendor (https://support.google.com/adxseller/answer/1074250?hl=en&ref_topic=6032302&vid=1-635808941398184317-2930939970).
5. What are the approval process and creative restrictions (if any) if I were to publish into Google GDN/ADX?
6. Can I export out the creatives from XPO platform?
No, you won't be able to because the creatives are layered with all the different mechanics and tracking.