Do I need BIWS/WSP if I have the Rosenbaum book?

Yes, it 100% is

.

If you're at a business school or a target/semi target there are probably a lot of the pdfs floating around. They won't have the videos or the models but they're a good way to practice without committing to spending large sums of money

Yes

Absolutely, they can help compliment each other and sometimes explain concepts in a way that could be more easily understood from one or the other.

Pick up an excel and accounting guide from one of the sites. Build an operating model from scratch. M&I guides to understand conceptually what's happening on each model. Build other models (besides operating) using R&P models/book as a guide in terms of formatting and line items.

I'm familiar with R&P, M&I, and WSP.

Few key differences here. WSP's models are vertical and they build out drivers for everything. I actually think this is not helpful when first learning the operating model because you're really just looking to understand how the 3 statements connect line-by-line - the assumptions don't really matter. M&I guides are very good at breaking this down one line at a time, and tying them all together. They also have interview questions specific to just that topic/model in each one.

If you want the most comprehensive practical modeling experience I think just buying the R&P models that accompany the book, and working your way through them is the best. They also have a completed version of each, so if you really get stuck on one line item, you can look in their completed model and see what they did. They all have these completed models, but in terms of formatting I think these are the best and it actually matters when you're trying to visualize how all the cells link and models work together.

One thing I don't like about R&P is they don't break down the operating model. It's not covered in the book and they group the 3 statements on one page for the other models.

I would say get the R&P book and the workbook for really in-depth knowledge of the 3 (4) valuation methods. The M&I guide is also very good because it literally explains everything to you as if you were a 3 year old, which is what you want it to be tbh