I have one too & from the factory, it wasn't perfect. As I recall, the fence wasn't perfectly square to the table & it didn't seem to cut perfectly square at 90 degrees. Once I got the fence squared up vertically, the other problem disappeared. So now it's great. Not a substitute for a sled though.
I use a North 7700 series half mask that does not leak at all. The only complaint I have with it is that because of my huge honkin' nose, it gets a little uncomfortable after a couple of hours. They are not expensive, the cartridges are HEPA, inexpensive, & last a long time. Several months of heavy hobby use. Just blow em out backwards when they start to plug up.
A good acid test for sealing is to use the organic vapor cartridges & then spread a bunch of nasty smelling finish around. Any leak at all & you'll smell the solvent.
Respirators are a bit of a personal thing, you need to find one that is comfortable & seals well on your face