Need to prep for RE PE funds that buy operating companies and securities (in addition to real estate assets)

I'd think about it three ways - the technical metrics, corporate strategy, and the landscape.

Metrics are pretty much the same down to noi as with individual properties/portfolios. However, on the rev side, a REIT or re opco has more room to optimize revenue and set pricing strategy through rev mgmt. Likewise, on the expense side, there's more room to minimize through procurement (economies of scale). Below Noi, things get different. Corp g&a matters in a re company, so ppl typically go down to adj ebitda to capture it. Also know core ffo and affo, and why they are important. Note, unlike noi or ebitda, ffo includes interest expense, which is a very real cost for a company. Also, ppl will pay a lot of attention to the balance sheet. Total leverage ratio and net debt to adj ebitda (fwd and trailing) are the big ones.

For the above, I'd suggest looking through green street advisors definitions, which includes a ton of important granularity and is available online.

Qualitatively, when investing in companies you need to have a strong view on the competitive niche/strategy. What geographies are they in? What quality of asset? Do they do development? Are they transitioning from one focus to another? The ppl who invest in re securities are very risk avoidant and like simple strategies, hate development, and advocate formulaic approaches to capital allocation.

Know what companies are the major players in an industry and how they trade relative to each other - implied cap rate (nominal and economic), ffo multiple, affo multiple. Who's the best in class mgmt? Read some research reports and you should get the idea.

Really important for you will be to understand the current state of the public market vs the private - BC that's a lot of the arbitrage the big pe firms exploit. Easy thing to do is read up on what BX has done and the strategies they employ. Follow through the years - companies like Hilton, Brixmor, Equity office. There are some different approaches they will employ based on the situation.

I know this kind of rambles and leaves a lot out. It's a big topic that ppls entire careers focus on (including mine), so it's difficult to hit everything. But basically, read green street metrics, look at research reports, read old news articles. You can even build a company model, but I might not prioritize that. As Jim Rome says, just have a take and don't suck.

Edit: in metrics, I forgot to mention NAV - which is a huge omission. Green street definitions can be found here: GSA definitions