Ease of Plugin Creation?

I'm looking at moving to Grav from Wordpress. One of the main things I need in most of the things I do though are managing a video/sound repository and having that available on a page for people to search through (sermons for churchs mostly), as well as the ability to create forms for many different things and track responses. I'm mostly a php guy, and I know that php is difficult to mix with twig from what I've heard. So I'm just curious if these two main things I need would be creatable with Grav or if I need to stick to a database/php based solution for my needs?

Hi, forms are provided by the Form plugin, see https://learn.getgrav.org/forms/forms.

As for the video/sound repository, looks like a good use case for plain pages, and Pages Collections. You would not need a plugin for that, just create a new page type/template in your theme. You can then go ahead and provide a special admin-side blueprint, which will give you fields such as file uploads or other things to manage your repository items. It's the equivalent of Wordpress custom post types.