I'm not big on plugins; in fact, I don't use any plugins. For my birthday tihs month, I have spread broad hints (leittle pink stickie all over the place and screen shots emailed to my fairy godmother, uh godfather that is, to get me a package of Topaz plugines. Those will be my first! I take it you mean where to store for access. Lol, IDK. Of course you would download to "downloads" and open them. I assume they will go to a default folder. Now loading brushes is simple enough; you bring them directly into the brush palette if you want frequent access or keep them in folders till you need them. My palette tends to get overfull and I have to reset it.
But I can guarantee that some wise ( _ _ _ ) member will be along to advise you. JK guys, I love ur knowledge. Without it, I would still be in the dark ages of PS6! I still have it on my old iMac and respect all versions of PS. And my gratitude to Adobe that they have always built on the software and not deleted very much in doing so. I still use all my same tricks, but man have I learned a lot since I joined this forum. Plus, I am always using my skills to help people or by engaging my time in the challenges and so forth. You would do well to enter one of these contests. Lots to learn and have fun at the same time. I "waste" hours and hours in Photoshop and love every minute of it. Even the painstaking pen tool renders. But the results are well worth the time.
I am currently working on the Spring Poster Challenge and it is a big job. I pen tooled gifs of ten flowers, yipes. Once I have finished, I will put them all here in a rar file for anyone who wants them. Yes, they are that good I can say with pride. And it is only by using it for years that I have gotten as fast using it as I can now. OK, I have gone way beyond your question here. My verbosity is well know on the forum. That's why they made me a mod. They know I like to gab so they figured I'd take every chance to answer requests! Just so I could hear myself think and tire the rest of you so you'd be too busy reading to make trouble.
Yep, I'm a narc, a hall monitor, and a spam killer. I also take a great toll on zombies. Apocalypse give me the heebee jeebies.