Scambaiting is simply talking to scammers as if you were a victim, but instead of being victimised, you waste their time. Why is this helpful? For every minute that they spend talking to a scambaiter, they are not spending it scamming an actual victim. Every call a scambaiter makes, they are technically saving people from being scammed.
No. This is actually counter productive. If you call from a visible number, they may just block you. If you call from a unknown/blocked/silent number, then they may block those. Otherwise, they can just rotate the number out of their system and continue operating. All of these actions take but seconds to undertake, so the total damage you can do by forcing them to burn a single number that quickly is next to nothing.
It depends on what scam you are targeting. The first step is to research the type of scam you are targeting. Let's say you target a classic Tech Support Scam. You would need a Virtual Machine (or VM) for the scammer to connect to (because you don't want them connecting to your actual computer). Another thing you will want to do, is find a way to securely call them (not using your real phone). You also want to hide your IP from them with a VPN (see online-security).
The basics are simply getting a VM running with Windows on it (Windows 10 is recommended). Then you need to make it "stealthy" so scammers don't realise its a VM and think its a real computer. Jim has a tutorial on this too: https://www.youtube.com/watch?v=6TM45vNI4Qc. You can use either Virtual Box or VMware to run the VM.
VMware is the professional product, however VMware can be pricy. Virtual Box is free and open-source, but doesn't have the same feel as VMware (in my opinion). Jim Browning uses VMware. There is a free version of VMWare but it has some fairly hefty limitations on it.
You can do this a couple ways, you can use a free app like https://www.textnow.com/ or https://bobrtc.tel/, or you can use a VoIP service. VoIP services are generally not free and will require at least some basic technical knowledge to get going as you will need a phone that supports VoIP OR (more commonly) a softphone, or 'application/app', on your mobile or computer to setup the VoIP service in.
You can share any information you have discovered with the community on websites like scammer.info or learn more about submitting to the authorities via the I've been Scammed page.
Check out the I've been scammed page for more information.