Zillow Group (NASDAQ:ZG) reports second-quarter earnings after the market close on Tuesday, Aug. 4. And with shares of the online real estate specialist down nearly 20% since last quarter's mixed results in May, you can bet investors will be listening closely to what the company has to say.

Analysts, on average, expect Zillow to incur a loss of $0.25 per share during the quarter, while revenue should more than double to $168.8 million. But Zillow's business is about more than just revenue and earnings, so investors should dig deeper to understand what's driving those results.

Here are four questions I'll have at the ready when Zillow's report hits the wires:.

1. How's the integration going?
First and foremost, Zillow Group CEO Spencer Rascoff insisted during last quarter's conference call that "our top strategic priority for 2015 is successfully integrating Trulia and maximizing the potential of our increased scale."

He's referring to Zillow's acquisition of competitor Trulia, which officially closed in mid-February after a longer-than-expected approval process from the U.S. Federal Trade Commission. Then in April, shares of Zillow plunged when Rascoff called 2015 a "transition year," noting that the FTC's slow thumbs-up left Zillow "trending a couple quarters behind" where it wanted to be.

As of last quarter, Zillow had already integrated the two companies' rentals and mortgages businesses and resolved some "advertiser uncertainty," which temporarily affected additions and retention of agent advertisers at Trulia. Going forward, Zillow's primary aim is to finish integrating its currently disparate agent advertising products by the end of 2015. When that happens, real estate agents will be able to enjoy the higher value proposition of seamlessly purchasing media from the combined companies on a single interface, further accelerating the shift from traditional real estate outlets to online platforms. Listen for updates, then, on whether this integration is progressing as planned. 

2. Is all that marketing effective?
Next, Zillow also outlined plans to invest over $100 million -- or roughly 15% of this year's revenue -- in a massive national advertising campaign designed to fuel its growth and further increase the scale of its combined businesses. And that's not an arbitrary figure. When asked to elaborate last quarter, Rascoff insisted that in coming to its target ad spending budget each year, Zillow carefully weighs a combination of its desired margins, employee headcounts, and the return on investment it believes it can achieve focusing ads on each of its four consumer brands, including Zillow, Trulia, HotPads, and StreetEasy.

Of course, arguably all but the headcount are potentially subject to wide fluctuations with each passing quarter. But investors were pleased three months ago, when Zillow said the early results of its targeted campaigns were encouraging. For example, Zillow reserved some of its marketing budget to launch its first ever ad campaign last quarter for StreetEasy, its New York City-centric real estate site. Thanks to the largely humorous ads it's placed throughout the city, Zillow saw all usage metrics at StreetEasy -- from traffic to page views and leads -- increase at least 50% year over year. Investors would love to hear more similar advertising success stories on a broader scale with Zillow Group's other businesses.

3. Are agent advertisers still loyal and growing?
Relatedly, I also want to know whether Zillow's agent advertisers are still growing in both loyalty and number. At the end of last quarter, Zillow Group had 103,415 agent advertisers, including organic Zillow additions and Trulia's existing base.

In a testament to loyalty, Zillow's average monthly revenue per advertiser in Q1 rose 23.8% year over year to $354, with around half of that growth coming from advertisers who have been with Zillow for at least one year. In addition, over 60% of orders were to existing advertisers purchasing more impressions. Ideally, we'd like to see growth in all these metrics sustained or accelerating from their previous trends.

4. How quickly is rentals revenue scaling?
Finally, I'd love to hear more color on the progress of Zillow's Rentals segment. When Zillow initially announced its acquisition of Trulia, Rascoff expressed excitement for the "massive scale" Trulia brought to the table in the rentals space. That scale was beginning to manifest itself last quarter, as Zillow announced it had increased Zillow Rental Network partnerships by 84% year over year, while almost 90% of the 50 largest apartment managers in the National Multifamily Housing Council counted themselves as Zillow Rental Network customers. Rascoff also confirmed that Rentals had already "significantly exceeded" early revenue ramp-up goals of reaching an annualized revenue run rate of $10 million within four years -- which is how long the more mature Mortgages business took to reach the same milestone -- and elaborated that Rentals is now on pace to exceed Mortgages' current $40 million-per-year run rate "within the next few years."

In June, Zillow also launched "Zillow Rent Connect: Boost," a new ad program aimed at multifamily partners that allows property managers to purchase prime targeted ad space above renters' relevant search results on Zillow. Over both the near and long term, this new program should only serve to further bolster the shift in advertising revenue to Zillow's online solution in the rentals space. Keep your ears open, then, for any color on how Zillow's latest efforts to monetize its rentals business have fared.

Steve Symington has no position in any stocks mentioned. The Motley Fool recommends Zillow Group. The Motley Fool owns shares of Zillow Group. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.