In general, SSD drives are faster but smaller than rotating drives. If you need a little more storage, replace your existing drive with a bigger one. If you need a LOT more storage, and don't need it to be internal, then something like a WD "My Cloud" plugs right in and offers a lot of storage
WD My Cloud 2TB Personal Cloud Storage WDBCTL0020HWT NESN
Most laptops have limited sound quality built in, especially if you're using headphones. There are a vast selection of external sound cards and DACs available at price points from $20 to thousands, depending on what you're willing to spend. If you're using headphones, make sure you get one rated to drive headphones, not one rated to just drive electronics. I have this one:
Turtle Beach Corporation
and feel it's a good value for the money.