Replace SBS 2011 Essentials with new Domain Controller running Server 2019 Datacenter

I am in a home environment with SBS 2011 Essentials running as the DC, AD, and file server. I would like to retain the domain name, retire the old server and replace with one running a fresh install of 2019 Datacenter. In 2011, SBS I name my domain JNET and .local came afterwards. Not knowing better, I left it. I have read several articles yesterday about how retaining ".local" is a bad idea and one should use an actual domain you own. I own several, so that is not an issue, but I don't want to have to rejoin a new domain as I know it requires you to create a new user on your PC which may not be a huge deal.

I have a couple of questions I was hoping someone could answer:

1. Do I have to retain the old server name? I would prefer to rename it
2. If I keep JNET.local, will that hurt anything? The biggest complaint I saw was that a certificate authority would not issue you an SSL if you had a .local. I am at home and a learning novice so I am not sure if I will never need a certificate but if I do, I would hate to have pigeon holed myself out of one.
3. One PC username is username.JNET. If I name the domain JNET.domainIown.com, will that mean all the PCs in the house have to join a new network? Will it also mean that the users in under C:\users will change from username.JNET?
4. Since I have datacenter, and can install unlimited VMs with hyper-v, I want to build correctly so that I better learn. Would it be better to have a VM for with role of AD or is it ok to put AD as a role on my new DC?

Thanks in advance!