I'm not sure exactly what your issue is sorry Suresh, Can you explain it a little more? Maybe the blog post will help you understand the Sugar Track: https://care.king.com/en/blog/article/candy-crush-sugar-track-is-here
If you uninstall the app you lose all your boosters, it's just how the app is. If you paid for anything then in the settings you can click to restore your purchases but if they were freebies you had saved up then I'm sorry to say but they are gone.
No major reason, its just that not all players have this feature. It seems to be a test still. Hopefully it will be something that all players will get at some point!
It's just part of the game. If you play a lot of the King games you'll notice that there are always differences between the games on Facebook and the mobile games like the daily bonuses etc.
I think that with 1000 levels you're bound to come across the odd level or episode that you don't get on with. If every level was a fly through the game wouldn't be as fun in a way.
If you're on 650 and the game is showing the under construction sign then I think you need to update the game. There's over 1000 levels available now. Hopefully this will also help your connecting issue as the updated app will have all bug fixes etc.
I don't think it is, well I haven't see a way. The game is saved to one account and that's it. I guess its to stop other people transferring their levels to other people etc. You will just have to get through those 500 levels on your other facebook ;) haha
I just watched a video of someone doing it. It looks a little tricky but if you can set up something similar its perfect. I hope this helps: https://www.youtube.com/watch?v=SK4pLYoAIRQ