I 2nd the Seismic Design Review by Hiner. Didn't do the classes either, just studied the book and did practice problems. Passed first time and I'm in geotech.
As for regular PE, I got the Lindeberg Civil Engineering Reference Manual just so I didn't have to bring every college text book. Great for the breadth portion of the national exam. Brought my college geotech books for the afternoon depth portion.
PPI PE Civil Reference Manual, 16th Edition – Comprehensive Reference Manual for the NCEES PE Civil Exam https://smile.amazon.com/dp/1591265703/ref=cm_sw_r_cp_api_glt_fabc_8MRKB182QE9XA945PVEF
Edit: typos
Refer to the last couple pages of the exam spec found here. These are the codes that you will be referencing during the exam, primarily in the depth portion.
I'd recommend the Civil Engineers Reference Manual (CERM) for studying. It covers a wide array of topics and can be used as a refresher while your studying. Here is a link to this book on amazon.
Prices keep going up on them. I bought a new one 2 weeks ago for $117. Ebay has a bunch of used ones as well.
A couple of clarifications. I know you said this is your partner but I am going make it simple by using "you", "your", etc.
In general to get your PE you need to take an exam and pass and have 4 years of experience working under the direction of someone who already has their PE. This assumes you graduated with a BS in an applicable engineering program from a ABET accredited college. Every state has different specifics on the rules as in some allow you to take the exam prior to having the 4 years experience or some require you to wait until after you have the 4 years to sit for the exam.
So to answer your questions now:
(1) Varies person to person. For the PE I studied probably a total of 40-50 hours and took the exam approximately 1 year out from school. I know some people that studied for 300 hours. The studying does not count towards the 4 years of experience. Only working on real life projects under the direction of someone with the PE does.
(2) Again varies but typically the employer will help financially. I had my employer pay for an excellent reference guide CERM as well as the fee for the test. I think they would have paid for a class but I opted not to take it and studied on my own. I recommend for self study to familiarize yourself with the required materials, do practice problems that you can buy, and practice exams.
2nd Edit: The CERM I linked might be out of date. Always get the latest one for the exam you are taking. While it might be an extra 50-100 buck, it could change slightly and that change might just be the question they ask in the exam. Also it is a great resource to have for early career engineers.
(3) This will vary by state by state, but I would suggest that your partner take the exam ASAP. So if they are in a state that allows them to take it immediately after they graduate, then do so. If you have to wait 4 years, take it when they reach the 4 year experience mark. There is an organization in the US called NCEES. It is part of the PE process and helps making the transferring of licensure from state to state easier. There is a possibility that a state may require your partner to retake the test. California is a bit of an exception and unless that is truly your end goal and where you want to end up, then I wouldn't plan your life around it right now.
Edit: In short, I wouldn't worry too much about your partner as while there are a lot of rules, there is a lot of fairly simple processes to make it pretty minimal effort to resolve.
most people call it the CERM (Civil Engineering Reference Manual) and its the bible of civil engineering. It was basically what i used for 90% of the PE exam.
The official CERM:
I actually have this one which i liked better: