Dash cam SD card

[Spikemixture]

Greetings,

Just had HU and front cam installed and working well.
3+ questions:

1. How do you know the memory card is full?
And when it is full what happens ?
Does is just stop?
Does it continue and overwrite the oldest?
I have a 128gb installed
And does anyone have any idea of about how many minutes/hours recording per GB?

2. The recordings are AVI. No big deal but can that be changed to MP4.

3. And lastly the app that comes with the cam is OK but has very few options.
Has anyone had success and a recommendation with another cam app on a Joying HU?

[Spikemixture]

Obviously asked too many questions for someone to take the time to answer.

What about just one?

What are the alternatives to cam app that comes with Joying HU.??