The synth for p-benzo from hydroquinone/H202 listed at Rhodiums page is set up for yielding 50g p-benzo from 55g of hydroquinone. I'm curious to know if anyone actually tried this synth at a larger scale, say, 100-150g of hydroquinone. Would it be simple enough to double all quantities if one were to scale the reaction at 2X?

Yes.
Usual you don't need to scale the solvent with 100%.

The synthesis says that a 4-neck flask fitted with an addition funnel and thermometer are required. Does the thermometer need to be submerged inside the reaction contents, or does is just need to be suspended inside the flask?

I use a 3 neck flask and yeah submerge the bulb of the thermometer to get a good reading...

blaaky

Hypothetically speaking, is the synthesis difficult? How important is tempurature monitoring? Are there any comments or suggestions that you might recommend on the synthesis?