signing into media and purchases will i lose my information if i sign out of media and subscriptions and sign into a different account?

If they are purchased media tracks then they will remain on the device even if you sign in with a different Apple Account. If you were paying on a monthly basis then you have a subscription and that is tied to the account with which you took it out.

Note, however, that if purchased and you later get a different iPhone you may have want to have them on the new iPhone. This can be done by syncing with a computer or by re-downloading from Apple (but Apple cannot guarantee the tracks will always be available in its store). This will require being signed in under the old account.

If you truly need to use a second account, it is possible to be signed into Media & Purchases with a different account, but then that applies to all apps and media, along with associated linking of data to that account.

In general it is not a good idea to use more than one account because of the above and other issues.

It depends upon how/where the data are stored. If they are stored associated with an Apple Account then you need to be signed in with that account to get access to them. If they are not stored with that account then you won't "lose" them. The loss may also only be temporary for as long as you are not signed into the account using them.

As I said, it is going to be specific to the behavior of the app you are using.