It is safe and recommended.
Use HBG and/or JITS to install games, updates, and DLC from the Switch. Make sure you're using 90DNS and/or Incognito to prevent a ban.
Use the latest Atmosphere and fusee-primary from
here, and use the latest signature patches (when using fusee-primary)
here.
eBay, Craigslist, here on GBATemp sometimes, etc. You might also get lucky at a used video game store or even a retail store. Always check the serial number before making a purchase.
No. TX might come out with a solution for these units in 2020, but we don't know how long it will be (if ever) before they do, and the process will likely be cumbersome and require disassembly of the Switch.
Buy an unpatched model and use the RCM exploit. You will need a USB-C cable. You will also need a jig of some sort for the first time you enter RCM. A properly sized paperclip works just fine.
To avoid being banned, keep the Switch offline. You can also install 90DNS and/or Incognito to block Nintendo's services, which will prevent your Switch from being banned.
If you want to use online play, you need a clean sysNAND for online play, and a dirty emuNAND for all hackery.