About the iPhone cloud storage?

Okay so I have the iPhone 5s and it comes with 5gb for the cloud free and it looks like maybe 12gb of memory. If I get more of the cloud usage will that add to the memory of the phone. Bottom line is I want to put more music on my phone. I'm not at all familiar with apple or iPhones in general.

5gb free? Yes. But that really works as a 'mirror' or backup. 12gb? Must be what's left on your phone currently. Does it add more to the phone if you buy more? No. Apple is locked and sealed on memory unlike Android. Your phone, your coin, your choice but I'd advise, just load your entire library on iTunes locally on pc. Mine is about 17gb now. Then create playlists and port over to the phone what you want at the time. I use a 16gb 5 and keep 600-650 on my phone at one time and zero problems. Still room for apps and other stuff too. Best luck.

I'm a tuna, I'm tinned in brine

Cloud storage is for backup and now Cloud Drive features only. This has nothing to do with the physical memory on the phone. If your music is on iTunes, when it is in the cloud and you have Wi-Fi or LTE (cellular data), you can stream it to listen (i.e. Play it from the cloud), or you can hit the little cloud icon and download it on your phone and play it without streaming (so do this when on Wi-Fi so you don't use cellular data).
I have no idea what your phone's memory is, presume 16GB. So for most people they can load just about all music they own on the phone if they wish. You can manage the memory of the iPhone in the settings app.