It should work. It’s just that react-native-gifted-charts specifies a version of react-native-svg of 13.x.y where x >= 6, while npx expo install react-native-svg will install version 13.4.0. There are a couple of ways of dealing with this:
Yes, except if by “as usual” you are referring to Expo Go. You can definitely do something like that, but you will have to create a development build to use instead of Expo Go.
I’m not 100% sure what you’re asking. But basically if you create a dev build and then want to install react-navigation you’ll need to create a new dev build.
There’s a free tier. So e.g. if you’re creating fewer than 30 builds a month in total (or 15 iOS builds) and only one at a time, then you don’t have to pay for that. If you’re using EAS Update it depends on how many updaters there are per month.
You can also build on your own machine and it would be possible to implement your own update server, in which case you wouldn’t have to pay Expo anything.