Congratulations on your 245!

My experience with smog checks is in Washington, not California, so take all my comments with the appropriate "YMMV"...

A failed or leaking exhaust would allow in excess air into the exhaust, and the exhaust gases may leak out before they get to the test probe. In WA, this would mean that they can't obtain an accurate gas sample, and the car would be failed. I would fix the exhaust first.

If everything is working correctly, and the car passed a little over a year ago, (which suggests no major problems present at that time,) you can probably have a reasonable expectation to pass just fine.

I usually do a good tune-up prior to the smog check. Not that the car necessarily needs it to pass, but it's a good reminder for me that it's time to do it. My dad on the other hand will run it through as it is, and worry about fixing things after it fails. I vaguely recall that CA will label your car a "gross polluter" or something if you fail several times in a row, so you may want to do the tune-up as a preventative measure.

Yes I have failed a couple of times, most recently because my fuel pressure regulator was on its way out and was causing the car to run rich. I would have had to fix it anyway, so it wasn't a huge crisis. In WA, as long as you can pass the test, they don't care about what's under the hood - I think CA is a little different, with any modifications requiring approval of the California Air Resource Board (CARB). For a stock car with stock parts, I wouldn't think it would be an issue.

Good luck!

Roger