Sherry:
It does sound like you're diving right in!
As for broken bits, I think we all do that...I have a small JAR of them
The good news is they recycle carbide.
The bad news is last I checked, you have to have 10# of the stuff
Yes, purified (filtered) or distilled water will work properly. The seals are just normal neoprene o-rings, so they'll be fine. A few drops of bleach every couple months will help keep mildew and mold from growing. Also, keeping a lid on the bucket/reservoir will keep down the amount of yuck that forms over time and potentially gets up into the tubes.
I happen to use car antifreeze, but in hindsight, I can't recommend it...my issue now is getting it OUT of my system
The spindle works best when WARMED UP a little. Typically about 5 minutes running at about 3-5K RPM will allow the bearing grease to distribute in the spindle. That will make the cuts more accurate and make your spindle bearings last longer. Also, leaving the pump running after a hard run, so it can continue to cool the spindle motor after it's stopped, is a Good Idea.
Hang in there; it's an amazing creative outlet, but as you're seeing, there is a VERY steep learning curve at the very start.
Once you get more familiar with all the weird terms like Feeds and Speeds (F&S), step over, depth-of-cut, pocketing, profiles, ramps, post-processors, GCode and man more, things will start to make a lot more sense.
And, as you're finding, there are a BAJILLION stupid little steps that have to happen every time we use the machine. It's like so strange form of Kabuki theater we have to act out each time. And, removing that probe magnet is one of them.
There is a way to (almost) never have that, but you probably want to stick with the basics for a while yet.
Check back here; I'm back and answering questions, so I'm happy to help. Yes, Happy. Try searching the forums here as well; lots of great information. There's also a FaceBook forum at
https://www.facebook.com/groups/SharkHD4Owners though these days I can understand why someone might be avoiding all of the anti-social media platforms.
In addition to learning about the Shark machine, may I suggest going through the CNCCookbook.com's CNC introductory sessions on F&S and GCode. They describe in great detail the actions that occur during cutting, which helps a LOT when it comes to understanding why the system didn't do what we wanted. I found them helpful for what we can do on the sharks, but they also go way above what we typically can. Which, is good, because it gives us a little more context of where our machines sit relative to others.
Hope that helps, and welcome!
Rando