100k is probably the limit to about any spark plugs. I mean, I did get more than 150k out of my 2002 4Runner and she was missing like crazy because of it. I won't go as long again. Which reminds me...I'm at 260k. I better go check them.
For the Mazda 5, you're due. I would only replace them with OEM. I haven't done it yet so I can't kabitz on how easy/hard it is. But I'm pretty sure my 2010 has all of them on top under the plastic cover.
Get a 5/8 (16mm) spark plug deep well socket. Nearly all plugs are this size. They are special and come with a rubber insert inside so the plug doesn't fall out or get damaged. You will need an extension too.
Get dielectric grease and smear that stuff in the boots.
I do not know the Torque specs for these. You should Torque them properly. As a reference my 6cyl 4Runner is about 15ft-lbs I believe.
When putting plugs in, never use your ratchet at first. Always just by hand with your extension to get it started. A cross threaded plug will not be a fun time.
Edit: I originally said to replace the wires too...but looking around...I guess not for this engine?
These days most people seem to prefer spark plug wrenches with a magnet in the top rather than the piece of rubber. The rubber often grips the plug too tightly and when you try to remove it, the plug wrench comes off the extension and stays in the well. The magnets grip less hard and come free (come out).
Check the service manual re: anti-seize if you like. I’ll never put plugs in an engine without it except for urgent, very-short-term use. Most manufacturers tell you to put a _little_ on the threads (in the service manual), and my experience from the past 3-4 decades is you’d better use it.
I have 2 Honda manuals and a Mopar one here that specify it. Frankly, it wasn't my intention to have a 'who specifies it' discussion. Long experience shows the benefits outweigh the theoretical costs, but one must use it _sparingly_ and appropriately.