You'll want to try BBQ and tacos while you're here. Most BBQ places that prominently display meat by the lb have good BBQ, and most places that make their own tortillas have great tacos. You can't go wrong most places so long as you do a normal review/menu check. But if I want BBQ I'll usually do La BBQ because their lines are reasonable and I'll do tacos from Veracruz.

Also try queso somewhere. And, most groceries stores sell excellent and fresh premade guacamole.

If I'm looking for guilty foods I like: Bird Bird Biscuit (buttermilk biscuit sandwiches), Rockman (coffee/pasteries/deserts - and across the street from La BBQ ... they have good bagels but my favorite is the Basque Cake), Jewboy (burgers ... we like their sliders "double meat, double chese, add bacon" ... great queso too), Casa Columbia (columbian), Cabo Bobs (burritos), Donkey Mo's (Korean fried chicken), Sangam Chettinad (south indian - in north austin though), Via 313 (detroit style pizza - I order "extra cheese, extra crispy, double cut"), Ramen Tatsu-Ya, Cafe 1886 for cinnamon rolls.

Date night: some of the places above are okay for date night, but we like yakitori from Fukumoto, Oseyo for Korean, and Buenos Aires Cafe. Most steakhouses are good. Three forks accepts bitcoin.

Day drinking with outdoor seating and strong austin vibes: Lou's.

Things to do (I don't do much so you'll get better recs elsewhere): barton springs pool (huge natural, public pool at the outlet of a spring ... also adjacent to a great park), standup paddleboard on the river, watch the bats fly out at dusk on the south congress bridge, wildflower center if you come before summer hits, go on a bicycle tour, go to a live music show of some kind, go to a range and practice the 2nd amendment :P, improv scene here is hit or miss, standup is pretty banging, Violet Crown for movies (divey old school place downtown), go to a soccer game (which is in season afaik) ... if you want to hit bars, I would recommend East 6th Street (east of I-35).

With more targeted asks I can probably give more specific advice, or ask others here.