I am a firefighter, an I am considering the upgrade to an Android Phone only to use an App called Active 911. This program gives Call Information with Turn by Turn Mapping on the Android Phone. The Share Everything Plan does not make financial sense for me just to support this App. If I upgrade to Android on a $1.99 per MB Data Plan perspective, could I still use the WiFi feature of the Phone for Data Access without Data Charges?
Yes, you can use the data features of a phone via wifi without a charge. I still have the original Android phone I purchased from T-Mo. I have no contract or service with them. I use the phone when I am working in the yard and around the house. I can still access GMail and Exchange mail. I also use Google Voice, so I can listen to my voicemail and tell when I have missed a call. If the call is important, I will use my VZW phone to return it. So wifi access is not plan or carrier dependent (although, wifi calling may be subject to carrier restrictions). I am not sure how this applies to your application, if your app will work on WiFi only, or if it will work away from wifi and data, etc. $2.00 a MB seems pretty steep to me, and given that a MB of data is nothing, you would quickly rack up the cost of a monthly GB plan.
tl;dr: There is essentially no charge for data through wifi access.
You can't get a smartphone without having a data plan. If you're a new customer you have to get a Share Everything plan. If you are a current customer you'll have to get a $30 data plan minimum that has 2 GB of data or you can get a Share everything plan.. Even if you could get the $1.99 per MB I wouldn't. You do realize 1 MB is 1/1024th a GB don't you? You accidentally use 14.1 MB in a month and you're paying $30 anyways. 14.1 MB is nothing.
And yes you can use wi-fi without incurring a data charge. I'm just wondering how you are going to get the info on the app via wi-fi while you are on the road?