Wireless is a myth - Run a wire!

If you want to control the projector, then it can still be controlled via IR remote, but for solid control, you should look towards a reliable control system which can properly turn the projector on/off and ensure it is on the proper input.

What size screen are you currently using? 15' diagonal is a big screen and typically demands far more than a projector rated at 3,000 lumens.

If I were looking, I would go with something from this list:
http://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&mfg=&p=500&p=3000&w=&r=&br=&ll=<g=&t=&db=&dt=1.0.0&c=&ar=Wide+%2816%3A9-10%29&dvi=&wr=&pjl=&pjw=&pjh=&td=25&is=180&i=d&tr=&oop=1&sort=brt&sz=15

You should expect most of the professional projectors to be 16:10 aspect ratio native, and then have the ability to work with a 16:9 screen if you use one. Sony has a fairly inexpensive 1920x1200 model which produces a fair bit of lumens for the money, and Panasonic has quite a few products which fit the bill.

1280x800 or 1920x1200 are both great, but I wouldn't pay more for 1920x1200 if all you are doing is PowerPoint and viewing from a fair distance away.

Please be aware, they do make wireless receivers that work with many products, but those are external to the projector, and should be treated as such. It's a terrible idea to ask Panasonic to maintain a open standard wireless receiver when 'standards' don't exist for wireless. Airplay (Apple) and Miracast (Windows), and a long list of others which change all the time should be purchased from a company which will keep up all those standards and keep things working. Also, if you need something new, then you can buy it and add it on.

But, mid sermon, expect video to just drop out - because wireless is like that.

If you want reliability, always run a wire. Always.