1. My face reddened as I was getting drunk.
2b. Essentially yes, although you can have a floor in say a car/aircraft/ship and these are not normally described as having an 'indoors'
2c. Not usually since 'floor' implies inside and 'ground' implies outside.
The only possible exception I can see to 2c - and it's stretching it a bit, is if you were to drop a cup whilst inside a tent which had a sewn in groundsheet. You might conceivably then use either floor or ground.
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