Im no sparky, but in my two poppers, the metal sleeve in the roasting chamber is earthed. It could be just a compliance precaution or something, but It looks like they went to some effort in the designs to make it difficult to reach the metal components. Id be a bit worried about the electrically conductive chimney now sticking out the top if there is any risk of it being live...
In my target popper, I max out at around 218ºC (bean mass temp); 225ºC would be handy.
I tend to roast 90g batches, and dont have any problems with beans escaping (no chimney). I do three roasts in succession, and it fills a 250g bag nicely. Mind you, mine is automated, so I can turn it on and walk away for 15-20mins.
And issues with tainting from the exhaust sealant?