256 GB would be plenty for what you listed.
You could just clone it using Samsung Data Migration. Then like corkyg said after verifying the clone was successful, you could add the old drive back in and format it.
You could also do a clean install if you wanted with both drives installed. I usually put my SSDs on SATA port 0 and 1, and you can delete the partition on your old drive during a custom install, create a new one, and direct your install to go on the new drive.
If you think you might make a mistake or are just not comfortable with doing it the two previous ways, you could just install your new drive and install Windows 10. After it is done, you could shut down your system and add in the old drive, and format it within Windows.
Depending on what SATA port you install the drives to, you will just have to make sure the drive you want to boot from is correctly set in your BIOS in the boot order. The options will be different depending if your use GPT or MBR formatting.