We have no reason to believe that Dumbledore wasn't looking for Voldemort
(I apologize for the double negative)
In the first several books we see very little of what Dumbledore does. He does not confide in Harry until Book 6, and presumably takes many actions that Harry is unaware of. For example, we only know of his plan to recruit the giants because Hagrid can't keep a secret to save his life.
Dumbledore tends towards subtly in his plans. If he had people searching the Albanian forests he would be using one or two quiet agents disguised as regular wizard hikers, rather than sending in waves of wizards to scour the forest. There is no reason to believe that anyone would hear anything unusual from their fruitless searches. Harry is even less in touch with the wizarding world than the average wizard. Why would he know?
Dumbledore couldn't have found Voldemort
"I was ripped from my body, less than spirit, less than the meanest ghost..."
-Voldemort, Harry Potter and the Goblet of Fire
Ghosts are translucent and capable of moving through solid objects. Voldemort was even less substantial as that. Here you can see the movie interpretation of that state, and I think that it's a fairly reasonable interpretation. But remember, that's after months of being strengthened by Quirrell's aid (possessing his body, consuming unicorn blood, etc). When Voldemort was in the woods he was probably even more wispy than that.
Ghosts are notoriously difficult to hurt (I believe there were comments to that effect in Chamber of Secrets when Nick was petrified), and Voldemort was even less than that. Even assuming that Dumbledore could track a grey mist in a large, dark forest, he has no reason to believe that he could catch or hold Voldemort. Maybe if he had a basilisk handy, but that's impractical for any number of reasons.
Add to this the fact that Voldemort was capable of possessing animals. We know that he spent a year undetected on the back of Quirrell's head, so presumably he cannot be easily detected while possessing creatures. Even if his ghost form could be spotted, that's another way he could escape that pursuers would likely not expect.
How did Quirrell find Voldemort?
Quirrell didn't find Voldemort, Voldemort found Quirrell.
"Then. . . four years ago. . . the means for my return seemed assured. A wizard - young, foolish, and gullible - wandered across my path in the forest I had made my home. Oh, he seemed the very chance I had been dreaming of. . . for he was a teacher at Dumbledore's school. . . he was easy to bend to my will. . . "
Voldemort, Harry Potter and the Goblet of Fire
It's possible that Voldemort is misconstruing events here in order to appear more powerful in front of his Death Eaters. But his words have a ring of truth to them. Even if Quirrell was searching for Voldemort, he is unlikely to have found him without aid. It seems more plausible that Voldemort discovered Quirrell's search of the Albanian forest and decided to reveal himself to Quirrell of his own free will, in order to gain for himself a servant.
How did Voldemort know he could trust Quirrell?
Voldemort was a skilled Legilimens, and capable of reading the minds and hearts of those he approached. Even if Quirrell was trained in Occlumency he would be unlikely to use it since he wanted Voldemort to trust him.
Even if Voldemort couldn't practice Legilimency as a sub-ghost (which seems unlikely, since he was able to detect Harry's lies while possessing Quirrell), his experience as a Legilimens would still contribute to making him a good judge of human character. He has some serious blindspots (love), but those wouldn't apply here, since Quirrell was interested in power and knowledge, axes in which Voldemort was the most insightful.
Even so, approach Quirrell was possibly a bit of a risk, but after 11 years it's possible that Voldemort was a bit desperate, and Quirrell probably seemed unlikely to have the skills to trap Voldemort even if he proved to be an enemy.
