Sam, first to tighten the blade to the proper tension, you should pick it like a guitar string, and it should give you a high pitched ping back. That's all I've ever done, and it's worked fine for me. Another way to test for tightness, is to apply pressure to the blade after it is tensioned. Use you index finger and press on the side of the blade, you should not be able to push the blade sideways anymore than about 1/8". To check for front to back pressure, you do the same thing. After a while, setting blade tension will become habit, and you won't even think about it. As for cutting 3/4" stock, it depends on what type of wood your cutting, but, you'll hardly ever use a number 7 blade for it. I mostly use a #3 or #5, but sometimes I can get away with a #1 like I stated it depends on what type of wood I'm using. As for what size to use in Olson blades I can't help you, I only use the Flying Dutchman blades and the numbering system is different. Yes, your blade probably has a bit of overcut, cutting forward at the top a little more than the bottom. Most saws do that direct from the factory, unless it's severe I'd leave it as it is. It probably can be adjusted by rotating the motor, but like I stated I'd leave it as is. To be sure that your blade is cutting as straight as possible up and down, you should install the blade to the back of the clamp yoke on the top as well as the bottom. I do that with my EX21, and I have never had any issues. For positioning the blade in the clamp, I make sure that the bottom clamp screw is over the blade with very little showing on the bottom. Then the top clamp screw will have any extra blade up through the yoke, but it won't be much. You could tighten the clamp screws up on the blade once it's in position, then you could use the tension knob to tighten up your blade. If you do it this way though, you're always frigging with the tension. Once you get the blade tension set, you shouldn't have to reset it every time you switch blades. If you insert the blade the same way every time, you shouldn't have to frig with the tension. I haven't touched the tensioning knob on my saw for a very long time. If you take your blade and attach the bottom clamp first, you can apply downward pressure on the upper arm of your saw while clamping the upper clamp. That will take the back and forth play softness your experiencing away, and it stops you from having to always play with the tension knob. It will make it harder to close the top tension lever, but, not that much harder. If you find doing this makes the top tensioning lever to stiff to close, then just reclamp the top blade clamp. I don't own an EX16, but I imagine the blade clamps are the same as on the EX21. I hope this solves some of your issues, if not, ask again.
Len