We're now just a day away from showtime for Sirius XM Radio (NASDAQ:SIRI). The satellite-radio operator steps up to post its second-quarter results tomorrow morning.

We know what Wall Street is looking for. Analysts see a substantially lower deficit for the quarter. They also see revenue essentially flat with Sirius and XM rang up as standalone companies a year ago. Cash flow should improve, however, as synergies are realized.

There are so many moving parts to the Sirius XM story that investors need to look at several other items in the report. Let's go over a few questions that I expect the company to answer in less than 24 hours.

1. How many net subscribers did Sirius XM shed during the quarter?
The good news during the operator's first quarter is that it landed 1.3 million new subscribers. The bad news is that 1.7 million accounts were cancelled. The market may not have expected a net subscriber loss of 404,422 listeners -- especially during a three-month period that found other entertainment subscription services, including Netflix (NASDAQ:NFLX) and DirecTV (NYSE:DTV), gaining ground -- but it's braced for another step down tomorrow.

The economy is still iffy. The "Cash for Clunkers" jumpstart for new auto sales came too late to factor into the quarter that ended in June. Sirius XM has also been inching its rates higher, by bumping rates on secondary receivers and online streaming in March. It began slapping an extra $1.98 a month on accounts to cover a new music royalty fee last week.

Losing 100,000 or so subscribers would be applause-worthy. Losing as many listeners as it did during the first quarter will bring out the boo-birds.

2. Are conversion rates still shrinking?
One of the more troubling metrics, buried deep in the first-quarter report, was the crummy conversion rate of 44.9%. In other words, for every 1,000 buyers of cars with factory-installed receivers, just 449 of them became paying customers after their free trials ran out. A year ago, Sirius XM was converting 51% of the new auto purchasers.

Is Sirius or XM a lousier value proposition these days? Is it the junky economy? Is the latest wave of car buyers just not into premium radio the way that the early adopters were?

The recession clearly is playing a role here, but Sirius XM had better hope that it's the only star. If lower conversions are here to stay, Sirius XM will have to move more receivers just to keep pace.

3. When will the ad revenues inch higher?
One of the major attractions regarding CEO Mel Karmazin is that he's an old-school radio guy. He cut his terrestrial teeth at Viacom (NYSE:VIA), so selling ads on the channels that aren't commercial-free should be a breeze.

These are dreadful times for terrestrial-radio marketers. Even the mighty Google (NASDAQ:GOOG) bowed out of the radio advertising market this year. However, net advertising revenue per subscriber fell at Sirius in both 2007 and 2008. One would expect its marketing reach to strengthen as it grows, but reality has gone the other way after peaking in 2006.

4. How are the App Store subscribers coming along?
The hype surrounding Sirius XM's foray into Apple's (NASDAQ:AAPL) App Store faded quickly after its launch. Howard Stern is still not available. Sirius XM continues to market the download as a free app, even though it is a premium service, even for existing owners of satellite receivers and lifetime subscribers who can stream online at no additional charge.

The app is unlikely to show us a flattering number. Is it so embarrassingly low that Sirius XM won't discuss it during tomorrow's conference call? This idea has the potential to be a juicy high-margin endeavor if radio fans pay up, so some insight is essential.

If successful, Sirius XM should be quickly porting over the application for use in BlackBerry and Palm (NASDAQ:PALM) Pre smartphones.

There's a great big world of opportunity knocking out there. Let's see whether Sirius XM is bold enough to answer.

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