Regarding the 2nd question, is there any document or reference material which I can refer.
Um.. I don't know... I have done it in the lab for POC.
The principle is this, using a static route to null 0, then router will passed to omp to other vEdges to receive, but on the advertis router use a higher policy to prevent the packet from being passed to null 0 (similar to the traditional Router's PBR practice)