If you use quality cable with an active mic (like yours) 25' is fine. As for the power, that should be fine as well. DC for powering the mic is generally much less of an issue than the audio signal. XLR mics and cables are ideal of course and I highly recommend using a professional mic with with a audio recorder that has XLR inputs. Using an adapter to plug an XLR mic into your camera isn't ideal. Either the cold conductor gets grounded, which is almost as bad as an unbalanced cable or the adapter uses a cheap transformer, which degrades the audio.
It sounds like a great movie, I just wish I could see it.
I will add; the lighting isn't always ideal indoors. I know you're on a limited budget with a limited crew, but even placing your subject a little differently and adding one light can make a huge difference. The sound is also fine but you should use a "dead cat" outdoors. Up-cutting speech is particularly jarring, which happens at least once. As for content, I was interested at first but got tired of Helen talking. I'd like to hear more location dialogue, even if it's irrelevant, but I admit I wasn't watching intently after the first five minutes. Do we ever see Rose? Why doesn't she talk? In short, not a bad piece but needs more depth as Mr. Tiemann said.
I'll add to this. With video, your biggest shortcoming is dynamic range in most cases. You lose at least a stop of DR in-camera just to white balance. If working in raw, you can use lens filters to handle most of the white balance and get an extra top in the highlights.
Here's an example I made with a hacked consumer-grade still camera to give you an idea. Top left if the camera's JPEG, bottom right is the processed raw image.http://www.gcmstudio.com/imagesonly/canon_a540_jpgvsraw.jpg
It's a drop-out. My first guess is that your SD card is defective or not quite fast enough.
I like elements of the idea but...
The retiree forced to take one last job is done to death.
The surgery nobody can afford is done to death.
You can still make a good movie with your plot (Hollywood literally has 80 some odd plots they've used for decades) but the characters have to be really compelling, which is hard to develop in a short.