I agree with bbkobabe about sanding the nut to round off the corners. You can use a nail file, emery board or a piece of fine sandpaper. Gently start to round that pointy corner. Do a little, try it. Do a little, try it. Etc. Just enough to make it comfortable. You don't want to weaken end of the nut. Stay away from the slots. Clean off any dust.
If you like the big, in your face, jangly sound of nylon strings, Aquila is hard to beat. Martin has a Nylon they developed with Aquila. These give you a "Hawaiian" sound.
If you want a more chimey, ringing sound, try a fluorocarbon set. D'Addario, Worth, Martin, Oasis all make very good fluoro strings. A warmer more guitar-like sound.
Go to stringsbymail.com or stringsandbeyond.com and read their descriptions of the strings they sell. I find the descriptions to be pretty good starting point in finding strings that I might like.
I used a UkeKrazy canvas & foam semi-hard case case for a year or so before buying a hard case for my tenors. It has rings for attaching a strap. It's pretty light. And the interior compartment will hold a tuner. The outside pocket can hold a spare set of strings and a cloth. Not as good as a hardcase for humidification.