Disclaimer - NOT my project, I just think it's cool.
I've been waffling about what language I'd like to use for AoC this year but if you've settled on Rust, you should check out this tool.
It will download your input for you and handle running and benchmarking. It also includes with some handy macros to hook generators to solvers, tailored to the format these problems generally take.
I'd gotten my heart set on F# as an intro to the MS ecosystem, but this is so dang cool. I do love me some Rust... it's going to be hard to steer clear.