I.P. Daley's guide is insanely detailed and worth a read, but to address your questions,
1. The MOTO phones have all of the applications that any other android would have. If your app is specific to the I-phone, you won't get it, but most apps are built for both Apple and android.
2. This all depends on how well Sprint works in your area. When at home, Republic will work off of your own Wi-Fi connectivity in your home - I haven't had any issues. When away from home, it reverts to the sprint network. I'm in an area where sprint is prevalent, so no issues here.
3. Republic Wireless's biggest rap is their customer service. When things work, everyone is happy and that is by far what happens 99% of the time. When there's a quirk however, (phone didn't transfer over, your MMS aren't coming through because you previously used Iphone, transfers from wifi to sprint network drops calls, etc...), there is no customer service # to actually call. It's all done online and through their forums, which can be untimely and prone to miscommunications. But that's also one of the reasons its so low price.
We've been happy and reached our break-even point 6 months in and are raking in ~100 a month savings now. This was before they had the more economical phones, so you might make out even better.
Rick