glad to answer your question s, as i too had many doubts with with method.

yes, it was a full sized towel provided by the hotel.
i did one shirt at a time. did the burrito twice per shirt. the towel was a bit moist afterwards but i think i could still have dried another shirt. i am a very small person though so it could be different for bigger shirts.

travel towels are on the thinner side so am not sure if they can take as much moisture.