let's start with luxembourg.
hostel: i stayed at the youth hostel luxembourg city (a member of hosteling international). it was super clean but the walls were comparable to paper (there was a large group of very young german students staying there and i could hear every word that i didn't understand). my roommates were a 40-something mother and her 13 year old daughter the first night and then one girl whom i didn't really speak with and one whom i definitely didn't speak with (since she stayed out all night) the second.
transport: i flew to lux from london and had no issues. i also took the bus to my hostel and then later from my hostel to the train station. very easy to use. for daily travel, i just walked everywhere. the old city is very small and easy to navigate but if you wanted to go further, bus.
food: om nom nom. i am very picky with food so lots of "traditional" foods easily slip by me, but what i did eat was tasty. very expensive, though, and i had a hard time deciding where to eat.
communication: everyone spoke english. nbd. moving on.
sights: i went into the petrusse casemates on a tour - super cool - and also did the bock casemates (self-guided). lots of stairs but really interesting to see all of the old stuff deep under the city! in general though, i just did a lot of walking around and looking at stuff, like the grand ducal palace and the golden lady.
nightlife: didn't do anything here so not sure. also, i was definitely not there during peak season - i felt like i hardly saw anyone plus the weather that week was awful - cold and rainy :(
like a boss.
grand ducal palace