With this hobby, you can go as crazy as your lifestyle will allow. You just have to remember that you don't need to get a crazy expensive system to make good or even great beer, but it can be fun.
HERMS = Heat Exchange Recirculating Mash system. The Picobrew Zymatic is essentially one of these.
Bowtiebrewery, not sure what secondary "parts and bags" you are referring to. Are you thinking the Picobrew Pico, which are packs you have to buy?
I've just recently gotten my Zymatic, mostly because I wanted precise control for rebrewing, I wanted to save time, and be able to brew inside. My thinking was if I wanted to build an electric indoor HERMS, I'd need electrical work and plumbing, then buy the actual equipment and it seemed like a much bigger project than I wanted to do, not to mention cost more than the Zymatic.
I've only brewed twice on it so far, but my advice really applies to any system - don't try to start off too big. There's definitely a learning curve and you'll be extremely lucky if you don't make a mistake on your first brew. You might think about doing a fake batch at first with just water to see how it all works. If you only want to do late addition hops, make sure you put the "pre-hop boil" time in. If you are doing a 1.060 or less wort, use the regular mash profile. The high efficiency mash takes 2+ hours, so I'd rather not do that if I can help it. I have a plate chiller and usually sanitize on my regular system 10 min before end of boil If you sanitize your chiller, be sure you use high temp hoses. I thought the one I used was, but it wasn't. That made quite a mess.
Good luck.