I have never had a smartphone before this. I have a laptop, desktops, etc. and have used Unix for years. I have read that there are some similarities in how things work on the S4 and those.
The memory in my phone is about 70% full. I have an SD card that came from my former phone that has some photos and music on it.
I have no idea how the S4 is making use of the memory.
Do I have to explicitly move things from on the phone memory to the SD card like I had to on my old not-smartphone?
Can applications be installed on the SD Card?
If I have stuff installed on the SD card, and I want to upgrade to an SD card with more memory, is there a simple way to do this?
What applications make dealing with this easier for the user?

Thank you all for your comments!
The memory in my phone is about 70% full. I have an SD card that came from my former phone that has some photos and music on it.
I have no idea how the S4 is making use of the memory.
Do I have to explicitly move things from on the phone memory to the SD card like I had to on my old not-smartphone?
Can applications be installed on the SD Card?
If I have stuff installed on the SD card, and I want to upgrade to an SD card with more memory, is there a simple way to do this?
What applications make dealing with this easier for the user?

Thank you all for your comments!