1. I think being forthcoming about it is very important. Especially when it comes to obvious unclear points/mistakes which are easy to correct. You should do that before attempting the commentary. The main reason is to save time (if correction is obvious, you might as well do it yourself) another is to show good attitude ("I try resolve this issue instead of nitpicking, see ?")
3.Imo it just derails the point. Good thing to do when dealing with unknown/emotional people, just adds clutter between "let's get to the point" people. Nothing wrong with that at some point but if you use it as first thing in the discussion it looks like tactic to influence emotions of other person.
I for one often get annoyed by too many niceties. I feel like someone tries to convince my emotions and not my intellect. It quickly becomes patronizing It takes time. It make me very suspicious of manipulation attempts; afterall if your point/offer is good, why not just present it and let me think about it. I don't want to be more likely to accept your point because you are nice to me. I want to take objective look at it, so keep being overly nice to after the discussion and/or everyday situations which doesn't involve resolving issues. I am not saying diplomacy is useless - it's great in every day relations and/or when dealing with emotional people. Among people who are good at discussing and just want to get to the point it should be kept to minimum.
>"Getting To Yes"
The title would be off-putting to me. I don't want to get to yes. I want to take possibly objective look at your point and I want you to take fair look at mine. The more I respect you the more I want eliminate emotions: positive or negative when discussing things.