Debating switching to PC gaming, have a few questions.

Alright, this may be long and I'm submitting from my iPhone so I'll do my best to have good grammar make it look nice.

So here are my questions and concerns:

1. I only have a laptop.
2. My funds are limited. I will be getting my student loan "refund" but I'm trying to be more responsible with it since I have to pay it back.
3. Is it worth it to build a ~$500 gaming desktop?
4. Should I build a desktop or invest in a newer laptop that I can use for more than just gaming?
5. Should I just stick with the laptop I have and use that until nothing becomes compatible?

Other comments:

1. Not being around my house often makes gaming on a laptop look very good.
2. Building a gaming desktop would restrict me as much as console gaming and cost more.
3. Maybe having games available whenever I have my laptop isn't a good idea during the semester.
4. Fuck, maybe I should just buy a goddamn book.

Thought, concerns, and comments are greatly appreciated; even negative ones. ( is a semi-colon after "appreciated" correct?)

Thank you for your comments!