The issue with hosting a forum is not "Beefiness of computer", but "size of upload pipe."
I can TOTALLY host a website, a SQL server, and a forum (Like simple machines-- exactly the software used right here on this site!!) on a repurposed wifi router. (No, not shitting you.) The problem is the number of concurrent connections, the bandwidth of sending the served page's data (Images, other content), and pals. (though in honestly, I WOULD pick something marginally beefier than an old router. I have an old NAS box that would be an ideal candidate.
It has a gigabit interface, a reasonably fast dual core processor, and 512mb of RAM, with a SATA disk controller.)
You see, your consumer grade internet service is usually *HIGHLY* asymmetrical. It favors download speeds over upload speeds, and they DO NOT want you hosting a server, of ANY kind. They often state such in their ToS agreement. When hosting a server, you want a big, fat upload pipe, and just enough download pipe to reliably get all connecting user's connection messages-- which is the EXACT OPPOSITE asymmetry to what a consumer ISP gives you. (unless you happen to have google fiber, and then you are great!) For the most part, if they catch you hosting a server, they will first send you a nasty letter, then they will suspend your service and demand you upgrade to "Business tier", which costs a whole lot more, or demand you down the server and never run one again.
Aside from this network asymmetry and ToS issue, there is also the problem of malicious actors. Remember when hackers compromised the core files of bay12's server a while back, so that it would produce meta data promoting south korean gambling sites on Google's Pagerank aglorithm?
Yeah-- THAT.
You will need to properly secure your SQL server, and will likely need to properly configure the host operating system that you are hosting your forum on. I would suggest linux, because you can run the web daemon and the SQL server daemons under different user accounts, and lock each one down tighter than a nun's knickers, but that's just me.
OR--- you could just pay a nominal fee every month for dedicated hosting for a small forum, and let THEM deal with the bandwidth, availability, and malicious actor problems.
Most people that get 'serious' elect for such cloud services these days. Your mileage may vary, and you might have reasons for self-hosting in an era that is averse to people doing that. Your call.
As for "Style" of software--- You might be better served by a properly done Wiki. (You know Wikipedia, right? Something like that, where each of your reviews has its own page, has a talk page, etc. Talk page might have a forum embedded.)