This is slightly awkward because at a scientifice conference you are likely to have poster presentations, demonstrations, etc as well as papers presented in lecture form. You might prefer 'presentations'

I don't think you can deduce from the term itself whether these are submissions or accepted papers, etc. It would probably be premodified as below, but in the absence of anything to the contrary I would guess it's the actual number of 'papers' being presented:
今回は発表演題数を29題に限定させていただくこととしておりましたが，応募演題数がこれを越えたため，査読により発表演題を決定いたします． ...
www.med.hokudai.ac.jp/~surg-2w/45thshogaken/endai.html