Hi

I would recommend the following:

   Blu-ray - this must follow the Blu-ray specification however I would up the bitrate to the maximum possible so that the movie will fit on the BD disc.

   Tablets - mp4 format, resolution is going to be an issue depending on the tablet - some will scale down video others will not

   Youtube - follow Youtubes recommendations.

   Archive master - this is going to be a problematic issue depending on how long you want to archive for and on what media.  You have to consider what video standards, media standards / availabilty and software functionality are available in the future.  If you intend to archive to BD or DVD disc then you will also have to consider media stability, storage conditions and availability -  almost certainly you will have to transfer to new media at regular intervals ie 2 - 5 years.

   Archive for later Editing - here you have to consider future software compatibility especially if you want to re-edit the projects again. Refer to Archive master above for other issues.

For archiving I always save everything related to the project, ie video, images, audio, music etc including material that I do not use in the current project., all my video is AVCHD or MP4, still images are jpg's, and audio mp3.

HTH

John