How do you tune the Tune- O- Matic bridge using the saddles? Does it cause or prevent fret buzzing?

It does help abit to lower your action if you lower the saddle. But lower too much will cause fret buzz.

My guitar had very high action. But lowering the tunomatic only causes more fret buzz, so what I did was adjust the truss rod to bow the neck abit then adjust the tunomatic. Now my action is perfect for me with minimal fret buzz.

But beware, if dunno anything about adjusting the truss rod, better don't DIY cause you might risk breaking the truss rod or break your guitar neck. Best option is bring to a luthier. You can try adjusting the tunomatic your self 1st to remove the fret buzz. But this makes the action a little higher. Hope this helps.

Ok... A bit complicated... But I get it... Thanks...

To intonate using the saddles, the screw heads are usually facing the neck, which is a bit of a problem trying to get a tiny screw driver in there.

I'd suggest plenty of time, a good work bench and a good accurate tuner.
Good lighting and tools help a lot.

Intonating usually will not cause fret buzz or remove fret buzz.

That can only be done with tune-o-matic bridge height adjustment or truss rod adjustment.

I hope this helps.