Sorry, the fram is solid, you can’t pop out the lens. 

No not a multi channel station. However you can add up to 3 additional individual sensors for temperature, not included with the kit. 

Of course it can be used. But since slides are made of glass, our microscope is equipped with 8 LED lights that reflect light during use. 

Made of glass, equipped with 5 blank specimen slides and 5 biological specimen slides. 

You can attach any Nikon F mount lens to it but there is no electrical contact so an AF-S lens will be manual focus only. Also there will be no metering so exposure will be trial and error. The aperture will also be stuck to its smallest setting, likely f/22 so the screen will be dark. If you have a "D" lens with an aperture ring then you can set it at it's widest setting to focus and then stop down if necessary. Similarly boosting the ISO to aid focus may work. I have a 90mm macro lens with an aperture ring and I set it to f/2.8 to focus and then rotate the ring back to my desired aperture if necessary. One workaround to help with the aperture would be to use either tape to hold open the aperture before mounting the lens or blue tack. Even with all the added problems to use an F mount lens with this it is still cheap and kind of fun.