I started out self hosting on a laptop maybe a little newer than yours. Pentium, 2gb RAM. I'm happier with my pi, but it's more than enough to get started on. Pretty sure pi-hole will run no problem, the others my struggle a little bit depending on your disk speed.
Your cpu will be a pretty limiting factor, but upgrading the RAM and putting in an SSD could boost the performance quite a bit.
Yes! I got a cheap .tech domain, and it kept increasing price year after year. Eventually it got a lot cheaper to just grab a .com.
Cloudflare has the best prices for domain names, they sell them at cost
That is probably an imposter
Matrix would be cool, if I knew literally anyone else who used it
Your 90 year old grandmother hasn't been paying a company to provide her with internet
If the phone is lost/stolen/damaged, your SD card could be inaccessible too. Your backups are your business, but you are opening yourself up to all kinds data loss if your only backups are stored within the device in question.
I daily drove a laptop with 8gb of RAM less than a year ago. Works just fine for most tasks. Granted, at Apples typical price point, I'd want more than that, but it is far from unusable. Running VMs wasn't fun though.