yogesh3188 To answer your questions:
1. Yes, this was the primary goal of the preview designer work. If it doesn't help, please reach out to me directly and I would love to figure out why so we can make it better.
2. It enables it for you as a user but you can go back to the GA designer at any time. You are not locked in to using the new designer and can swap back and forth. Only caveat is that when you switch, you must leave the blade and come back to see the switch back option. This as a technical limitation to how portal blade switches work.
3. Yes
1. Only the workflows you modify with it, when you go to a production logic app workflow, just switch back to the GA designer.
2. Generally no, that said: when you hit save, we don't just modify your workflow json we generate an entire new from the designer state, so we can't promise it. This is also how it happens in designer today. If there are any cases where you find this happening we would definitely love to hear about it.