16mm or 35mm have to be printed - this is expensive you don't have control over the process and if the print dosn't looks as you expected you have to repead the process... (in this case you would export a DPX sequence from Premiere and send it to the print service)
HDCAM requires a SDI framebuffer + tape recorder - if you don't own one - you have to export a 1080p25 DNXHD Quicktime file or something like this and send it on HDD to a video shop that will tape out your video.
Digibeta/ Betacam -> the same thing as HDCAM but you have to downconvert to PAL SD 720x576... this is a low quality option...
DCP - Digital Cinema Package: this would be the best way to ensure a high quality screening. But you have to create a DCP or find a DCP mastering facility to do it for you. In this case you also export a DPX sequence from Premiere (possibly also a 1080p DNXHD export will do the job...)
--> Keep in mind that you have to go 24p on film or DCP regulary - you can have a SMPTE DCP with 25p - but ask if this is a valid option...
Thanks for your feedback, nw42 - much appreciated. I think HDCAM looks like the best option for me.