It is really hard to tell, my eyes are certainly not what they used to be, but that looks a lot like dust. If those are scans from a local lab then they are not very careful to keep the work area clean. If they always happen in the same location for each and every frame then they could be camera or lens related. If not, then I would suspect the processing end. Maybe shoot another roll of film and send to a different lab to see how their scans look. Also, keep your negatives and go buy a loupe, 8x or 10x. When you see the spot in the scan, use the loupe to check the negative to see if it is on the negative.
As for image quality, contrast, etc., try shooting at different aperture and shutter settings. It likely is exposure related, but could also be developer related. If the lab's developer is becoming exhausted then your prints will reflect that by a washed out look to them.
Lots of things to check, just a few suggestions you might try.