There's a ton of technologies that where invented for war that, thanks to war, got enough funding to be reinvented for general use, the airplane is one example of something that wasn't quite frequently used before the world war, after that it adapted into mass transit, the military also heavily invested in radio communications thus making them more plentiful.
If everyone always agreed, we would be a very boring and stepford wife type of society. A little conflict keeps us on our toes. We haggle and then make united decisions. As long as the conflict doesnt turn in to a full out war, there should be no problems. Conflict also helps with variety, and variety helps with economics.
Yes, I think that conflict is good for progress. In many cases, conflict can lead to people examining multiple solutions and seeing other sides to issues, and this way, they can determine which solution is the best. This can easily lead to progress being made in a number of circumstances.
This has been true in the past and given human nature, would probably be true currently and in the future. For one thing, conflict can trigger increased government spending, such as wars needing increased production from the nation's factories. Additionally, conflict can lead to scientific and intellectual progress when scientists work on finding ever more destructive and powerful ways to fight.
One does not have to look much farther than how things are currently going for us in Congress to see that conflict is not necessarily a good thing in order for us to hope to one day progress in terms of how things end up going in this country of ours.