Account > Personal Settings > Web Client > Enable V10+ web clients (Performance for large accounts may be slow)
https://www.evernote.com/PersonalSettings.action
I enabled this setting, and all severe problems I was complaining for long are all magically solved.... Not just for Android client, but on other platforms, Windows, Mac, Web, Evernote clients are fully functional, more reliable, and run at reasonable speed. This is my first time to see V10 runs fast and do something properly, so it's kind of a touching moment.
Unfortunately this is not the solution provided by EN support. I was getting help from them and sent them logs and all, but they never mentioned this.