Review the photos of the various Two Stroke amp builds in the photo section to see how others have mounted the OT, the OT leads connect as marked “To OT” on the chassis layout. Review the schematic in the TAN wiki, it clearly shows how the OT is connected. Read DH’s explanation on the how to connect the secondary leads on the OT and wire the impedance switch accordingly.

The resistors to ground on the boost switch were not part of the original design, they were added to pre-load the “boost” caps and diminish the amount of pop heard when you select one of the boost settings for the first time when the amp is powered up. You could leave them off, experience the pop and then add them later. View the “Maggie” kit schematic on the Weber SVT website for another view of how the switch is wired.

The heater circuit is most often not shown in tube amp circuit layouts and schematics (but sometimes it is) for clarity as they are just about all the same. Review your “Dumb question dept” topic, the resources mentioned there offer a complete explanation of heater circuits.