Offline Profile

For a possible reason why your friend cant hear you

https://support.xbox.com/help/hardware-network/accessories/troubleshoot-chat-headset

Solution 1: Make sure your headset is not muted

Check that the orange LED light next to the mute button is not on.

Solution 2: Power cycle your Xbox One console

For help, see
How to restart or power cycle your Xbox One console.

For the Minecraft problem you can always fill in a request for support

https://help.minecraft.net/hc/en-us/requests/new

Actually, it is really easy to turn an offline profile into a gamertag with xbox live gold please review :support.xbox.com/.../offline-profile-to-gamertag

Unfortunately you can not merge an offline profile with an existing Xbox live profile. This will likely never change.

You can promote that offline account to an online account using the information here:

https://support.xbox.com/en-US/my-account/manage-gamertag-and-profile/offline-profile-to-gamertag

All of the achievements you got in the original game were unlocked offline. That may be the problem. If you earn achievements offline you must be signed in to that copy of the profile next time you sign in. There are 2 copies of your profile - offline and
online. They are usually always in sync. But if you take a copy to a mates place or have an offline console they can get out of sync. If you then recover your profile you replace your offline profile with the out of date online profile.

Well you have a major problem theb

Since you already created the accounr you can't use it again on the offline profile

You MUST UPGRADE the offline profile with another email address to use your offline profile online

Also should be noted that is only if you want to use your offline gamesaves

If not then use the new profile