Lesnar hasn't been seen backstage but it is not uncommon for them to hide him somewhere to prevent leaks from getting out. Lesnar is scheduled to face Universal Champion Roman Reigns at Crown Jewel later this month.
As far as tonight's WWE Draft, most of the talent will find out where they will be drafted at the same time as the fans watching at home. WWE management doesn't tell the majority of the talent to prevent leaks from getting out and this has been the case for many years.
Oftentimes, the top names will know ahead of time. There's been talk of some NXT names moving up to the main roster. Click here for news on the top candidates that have been talked about for a move to Raw or SmackDown.
WWE announced the rules for the draft and they are similar to last year. Half of the roster will be drafted tonight and the rest on Monday during Raw. Undrafted talents will be able to sign with the brand of their choice. Typically, the undrafted talent are the names on the lower part of the card.