Android App Testing - repost

We have an Android tablet app that interfaces with a USB device via USB-OTG. It has 15 to 20 screens in both landscape and portrait orientations, however is built for only one specific OEM device. We need all the functionality to be tested. The app is an embedded product so a full tablet along with the USB device will be delivered to the freelancer. The source code should also be inspected for any obvious problems with the code. Timeliness and attention to detail is very important and we require the project to be done asap as soon as it has started. Due to confidentiality, we cannot provide the app until an NDA has been signed.