[akhtene]

Well,trying to locate a ring in the space of M-E would be like looking for a needle in a haystack.
Sauron's intention to start a war seems quite sound to me, as it could lure a ringbearer within his reach. I mean, if Boromir or someone like him was keeping the Ring, he would definitely hurry to battle and attempt to use the Ring. As doug*platypus states, Sauron didn't believe the Ring could harm him, he just wanted it revealed.
Sauron simply didn't take into account that such power could be refused, and instead of drawing the Ring into his hands, got tangled in the war and let it slip away.