It's all open, you can come to whatever you want. You'll be wishing you brought your bike though.
For getting on the actual track, after hours and non-powered (bicycle) or foot traffic only. No E-scooters or the like. You *may* be able to get out on the track on a bicycle at lunch, but you'll have to check with the director to confirm...I've never tried but heard that it is possible.
If you have any particular questions, it's all pretty straightforward. You can also pit with someone else that's already going and have them show you the ropes. What're you riding?
Tech opens at 0700 with general riders meeting at 0815, then you can go to the novice classroom portion after that, then the new riders meeting after that. The only thing you'd miss without a bike is the new guys go out and then right back in again to get the procedure down for on and off. After that, you just follow CRs around to learn lines at a very reasonable pace. Is there anything in particular you are worried about or struggling with?
As for tech, basically make sure nothing is leaking (fork seals/oil/etc,) make sure your handlebars turn all the way in both directions, make sure your throttle opens and closes properly at both all the way left and all the way right, make sure you have plenty of tire tread and brake pad left, make sure nothing (rearsets) is loose, and then check the chain tension. Take some painters tape and cover the lights and the mirrors, and you're done.