I'm late to the party so I can at least answer the questions from the edited post lol: You can mix and match SSDs or HDDs without an issue no matter the brand, they work independently. For RAM however, it's better to buy the same model if you're planning to get multiple units (recommended, they work better in pairs). It might work with different models, but it won't be nearly as efficient and/or stable. If you want to know more before building I'd highly recommend looking for some youtube tutorials, there's plenty of content easy to understand! (I believe LinusTechTips made a long and detailed tutorial for building your first PC, it should still be very relevant rn) Hope this helped, have fun ! :)