What's the most efficient way to get from 2000 to 2300? I'm a hobby chess player with a rating of about 2050 FIDE. I would like to get to 2300 in the long run, but I don't have too much time on my hands, since I'm a busy university student and I also have other interests.
What I'm looking for is some kind of training plan that I can follow and that will eventually pay off. That comes with a few questions, of course. 
 1. What should I train?
 2. How much should I train each week?
Each week, I have about 4-5 hours available for chess training. My current idea is that I spend most of that on tactics, and some of it on reading chess books on strategy. What do you think?
Once you've reached a skill level like that one you have, it really depends on what you current flaws are!

The first step should be a deep analysis of your games (I mean a real self-made analysis, not checking what Stockfish thinks of each position) Try to find the reasons why you lose the games you lose.

But, in general, for a 200+ rating point increase, you will have to work to some extent on all aspects of your game, with tactics and strategy (static and dynamic) being most important, but I'd also have a look at fundamental endgame theory as wel as build a solid opening repertoire.

Also, is it a possibility to hire a coach?

Good luck!