Adding doch to a sentence can change the meaning in all sorts of different ways dependng on the emphasis
- Gib mir doch bitte Bescheid
can mean either "do let me know", or "let me know after all", although the first would be more likely - the kind of thing you'd say to somebody who has a habit of not letting you know. In the second case you could also say "Gib mir bitte doch Bescheid"
It in no way implies your are wanting yes for an answer
- Gib mir doch bitte 200 hundert Gramm von dem weichen Käse
probably means "after all". Although, spoken angrily, it could imply impatience: stop messing around and give me the cheese.
In either example another possibility is that doch is being used as a filler word to soften the directness of the request