Is this product full box set? or only CD case? I wanna box set..

Not a box set and not compatible with Windows 8.1

Will this game play on a newer Dell that had windows 10 or. 8?

You have to use windows compatibility options and it should play. I am having no issues with windows 7 , and Linux Mint on Wine .

Does the disk need to be in the drive to play or is it a one time download?

In this case the disk does need to be in there.

Is this a one time download, or do I need to put the disk in every time I play?

You Need To put The play disc in the disc slot everytime you play. I know this question was answered six months ago. Its an easy question you didn't even need to ask you could have found this out yourself, before asking. Questions could have found out without asking appearing in my email. after installing instalation disc than the cinematics disc play with the play disc. ive heard of a version where you download off a site without any discs but couldn't find it so I bought this original version.