NeurIPS openreview - can I upload paper pdf after abstract deadline or should I upload something first to be able to update it later? [D]

Hi, I have a question about openreview procedure as in the title. It’s my first time submitting to neurips so I’m unsure. Also for code URL submission can I do the same or should I put an URL in first? And side question, but does anyone know how neurips prevent people from pushing codes after paper