is it possible to have the status line on top of the window?

Nope ....

well, you can always download vim's sources, and go from there, but natively, no. Not that I know.

However, you say, you're looking at the top of the split to see what file is in there ? Why is that ? You can easily put all the buffer / file information in your statusline, and display it for every split out there (laststatus=2).

As far as tabs go, they were introduced under some pressure on vim's creator, but are rarely encouraged, as the way which to handle files in vim. Vim's "natural" way has always been window split + buffer manipulation.