You should check for h.pylori

Great to hear you have seen some improvements!

Yes perhaps you weaned off too fast. Ideally you want a clean diet and perhaps taking gavsicon or an alginate agent to aid the process too.

It could be LPR yes though not definitely. Search RSI on my site, its a test to help determine if its LPR related. Yes just need to come off them slowly while doing a good diet and so on.

You can try to taper off them like try taking a half dose and as I explained in this article. You could also try melatonin at night, it may help with the reflux, there has been studies backing that up. Taking 3mg -6mg at night. Over a period of 1-2 months you should see an improvement.

Yes you can take Prevacid, if you want to stop it I suggest doing a low acid diet alongside it and tappering as explained in this article.