I'd say definitely buy the book for 2P04 since it's also used again in 2C04 (Dr. Wilson is one of the best profs in Civil, but he's not super easy). It's also a good reference for other structural courses. These two courses are thought to be the most challenging in 2nd year Civil and you will see some people fail both, but if you put in the work they aren't that bad. Just keep on top of things and do lots of practice problems. Theses courses are also used in upper year courses more than the others (I'm in Structural btw, so I can't really say too much about water/environmental courses).
The course is now 4 units, instead of 3 like it was when I took it, but I didn't buy the book for 2B04 and I did fine, but I think they changed this course since I took it. I also didn't buy the surveying book (2A03).
2nd year math is brutal. I can't really give too much advice. I have a PDF of the solution manual to the text. I'm not sure if the same text is still being used, but I can send it to you if you'd like it.
As for management, I think you'll have 2AA3 (Accounting), 2MA3 (Marketing) and 2X03 (Econ). Accounting is boring and I never did well in it, but I don't think it's hard if you put the time in (easier said than done
). Try to get Vilks for 2MA3 and avoid Cossa if possible. If you have Aswani for Econ, he reuses his old tests, but in general this course is quite a bit harder than 1B03 and 1BB3. I bought all the books for the commerce/econ courses.
Let me know if you have any other questions.