For a basic intro, I would recommend “Principles of Communism” by Engels. It’s a super quick read, and it’s organized in a FAQ format.

Beyond that, it really depends on what in particular you’re interested in. For economics, I can highly recommend “23 things they don’t tell you about Capitalism” by Ha-joon Chang (although it’s more about capitalism than socialism). For learning about the state, nothing compares to “The state and revolution” by Lenin.

I’ve used the Gazzew u4ts with the new plastic, and it’s basically indistinguishable from the boba version.

You can also get boba u4s in black color so that they don’t discolor.