I wanted to clarify something, as a co-founder of one of these tracking companies (Tapstream, we do attribution tracking for free): when you're tracking installs from most ad networks, be it Facebook or someone else, the accuracy will be near perfect with most tracking providers. Ad networks in general support the use of IDFA or Google Advertising ID for attribution, which is passed to us on click. We then collect the same ID on install and send it back to the ad network so they know an install happened from that click. There's no guessing or fingerprinting involved.

If you're seeing divergent numbers you need to examine the whole chain for breakage - your ad network, the attribution solution and lastly, but most importantly, your tracking implementation.

If you mean the conversion rate is the same (meaning you're making a lot more revenue with the larger price), then that's the right call.

If you mean that your net profit is the same but you have higher unit sales on the first price I would go for the lower price to have more customers (and more chances to have them buy an IAP eventually, or leave a good review).

How close is the app to completion?

If it's almost done you should really do a soft-launch and prove some of your assumptions out (see http://blog.tapstream.com/post/71538606229/the-art-of-soft-launching ).

Otherwise, it takes a strong track record in building successful apps to impress investors, or some very unique domain expertise. The mobile app space is extremely competitive.

It can be pretty common. It's different for different networks, some will over-report and some under-report. Google for example generally under-reports conversions, so we adjust for that on our end. Social buys generally over-report due to bots etc. It's definitely annoying but once you get your baseline metrics down you can better estimate your true costs and revenue.

To put it simply: their VCs.

Take a look at who funded them:

Seed (12/2013) $1.43M
Google Ventures
Initialized Capital
SV Angel
Brett Slatkin
Harry Cheung
Fuel Capital
Index Ventures
Kleiner Perkins Caufield & Byers
S-Cubed Capital

Series A (3/2014) $8.6M
Kleiner Perkins Caufield & Byers
Garry Tan
Alexis Ohanian
MG Siegler
Bing Gordon
Megan Quinn
Chris Howard
Brad Silverberg
Vivi Nevo
SV Angel
Ashton Kutcher
David Sacks
Bill Lee
Pete Cashmore
Joe Montana
Rob Wiesenthal
Google Ventures

(from http://www.crunchbase.com/company/secret )

Many from this list are using the app, talking about the app (very often), and creating the air of inevitability. Their social networks are extremely influential. There were apps similar to Secret before, but none with such A List supporters behind it.

Facebook is a good start, but you might find iAds a little pricey when just starting since I assume you don't have all your metrics down yet, like LTV, ARPU, etc. These are very important since you'll know what you can afford to spend to acquire each user.

As next steps there are many networks I could suggest, depending on what your app is, including InMobi, Millennial, Ad Colony, Aarki, Greystripe, etc.

We really benefited from allowing ourselves ample time to test the app. Firstly, it helps you perfect the app but we found more importantly, it actually helped with the marketing.

We used TestFlight but HockeyApp is also great. (neither solution is a joy to use, mainly due to limitations Apple places on distribution of test builds). Getting 10-50 users to test is usually sufficient unless you're testing a multi-player game that requires more players to test the in-game dynamics. In those cases, it's often better to go straight to a soft-launch in a smaller English-speaking country (see http://blog.tapstream.com/post/71538606229/the-art-of-soft-launching )

I mentioned how your beta test can actually help your marketing efforts: use the beta to create buzz and aura of exclusivity around your app. Get people with large social followings to test it, enjoy it and talk about it before it's released. Have a LaunchRock or similar lander to capitalize on that buzz and to collect emails for a waiting list to use for launch. This can give you a serious ranking boost on the launch day!

Success should be defined relative to your category. If you're marketing a game your criteria will be different than if you're launching a 99-cent weather app. For example, take a look at download numbers required to enter top 25 in a few different categories:
http://thechocolatelabapps.com/downloads-app-store/

Your strategy to get there will have to also depend on your vertical, but generally it involves a mix of paid user acquisition (via mobile ad networks), organic acquisition through social, viral and web, and finally look at potential for dominating App Store search (ASO).

Make sure to look at their previous work, and that what you're building is well within their comfort zone. If you want to build an app or a game that breaks new grounds on UX or visuals you really do need the top talent to get you there.

There is no one "good" DAU/MAU number, they vary a lot: is the app paid or free? Is it free with ads or free with IAPs (or maybe no monetization whatsoever)? Is it a game or something else? Some games/apps with low DAUs (in tens of thousands) make more money than much bigger competitors so you really need to focus on specifics of your app. Let me know if you can share more details of your app...