This is 5 different questions. Please Ask one question per thread. Please also avoid references to competing software, since we haven't used it and it doesn't help us understand what's being described.
go opencontainer new will do that.
Change the new to newtab or newtab=findexisting if you'd rather open a new tab instead of a whole new window.
There's no way to do that at the moment. (I usually do this the other way around: Most text editors let you search a folder for contents and then cycle through the results or open them all at once.)
You could do that using a script which handles the lister-closing event, checks if the lister came from a layout, and saves the layout if so. (This would cause problems if you have any multi-window layouts, unless the script was made to only do it for certain layouts while ignoring others, which would be easy enough.)
We can help write the script if needed, if you link your account.
That's how it works by default. The viewer responds to clicks on files, but if you just change which side is active it has no effect.
You could use a script to change this if you wanted to, since there's an event to detect the source/dest sides changing and a command to load a specified file into the viewer. As above, we can help write the script if you link your account.
The viewer can open on the right or on the bottom, but not on the left.