Can I just upload the normal .php files to the server and will hiphop automatically compile the files on first request. Or do I have to compile the files before uploading to the server?
If I have a custom extension/module written in C, will it work with hiphop without any modification?
You ask two questions at once:
No, you need to compile them. Either before uploading or after uploading but in any case before the HTTP request.
Not out of the box. This has been answered here: