a random one: https://www.twitch.tv/streamhubpro

youd lose access to your stuff yes - but if lemmy follows mastodon, youll be able to tranefer your account to another instance but thats not available yet

you need an account on the instance to create a community there. but you wouldnt need multiple accounts to browse other instances, youd be able to find them though your account on the instance youd mod on :)