How to reload all tabs ?
I don't think there's a feature for this, but you can always enable the "Continue where I left off" settings and restart Opera.
How to move tab bar ? (at the bottom/left or right)
Not possible, but you can use extensions that adds vertical tabs, like this one: https://addons.opera.com/extensions/details/v7-tabs
After opening all bookmarks is it possible to remove one bookmark at a time ? (like for adding a link to a bookmark with the heart button)
Right now it's not possible to remove bookmarks from the heart pop-up, but that will come soon. Right now, you can right click on the page to open the context menu, and there you can select "Move bookmark to trash".
Is the menubar still exists ? If yes, how to enable it ?
I guess you mean some old Opera 12 menu, then the answer is no.
