Neo retro candidate?

I’ve got this schwinn that I picked up and I really like it. Rides and shifts great, stops okay, but the hoods. I find them uncomfortable.

I love the look of those cool neo-retro builds, and poking around on Ali express, Tiagra 4700 group can be had shipped for a few hundred bucks.

So here are my questions to the wise people who have tackled something like this before:
– Is a modern group on an old steel frame worth it?
– Is it worth saving a couple bucks with Tiagra or spending more on something else?
– I’d do all the work in between work and study, what are some common rookie mistakes to avoid?

Also, I’ve never owned any bike newer than a 1999 lemond Tourmalet, that is to say I have no understanding of how awesome modern shifting and braking technology has gotten since the 90s lol.

I would love something that feels snappy and fun, I’m not looking to be the fastest KOMmuter in the bike lane.