It is not strictly necessary to autoclave each of the chamber components separately. Although this might improve the effectiveness of the process, it is recommended to assemble the chamber except the lid before autoclaving in order to facilitate the sample insertion process.
Yes, all the chamber components can be autoclaved.
The window for visual inspection of the chambers is at the bottom of the chamber, so an inverted microscope is indicated for the inspection.
The glass window at the bottom of the chamber can be used to inspect the samples which is being culture without the need of removing it from the chamber.
However, only the samples which are thin enough to permit the light to go through will be feasible to be inspected under the microscope. Also the distance from the sample to the bottom window will determine whether the microscope inspection will be effective or not.
Having all these considerations in mind, the optimal configuration to allow visually inspecting the sample from the bottom glass window is combining a thin, plane substrate with the sheet-like grips, which maintain the sample next to the glass window.