I dunno! ;-)
Computer: Mac vs. PC; Use what you have until you know more. There is enough “tech” to learn in this business without adding a new computer interface AND re-learning how to use ALL the programs you use on that new operating system.
Mic, Interface, headphones: Call someplace like Sweetwater, Guitar Center or maybe a local guy downtown that supplies bands with equipment. Heck, buy local! Except- if that local guy ONLY does bands, he likely knows nothing about managing sound in a small studio or VO. You’ve been warned.
When you call the company, explain your hopeful budget, let them hear your voice while you talk, and be in the space you hope to record in. They’ll make recommendations based on all that.