Modeling for Different Transactions

In trying to understand the whole investment banking process, I've come across a pretty basic question: What models are used in different types of transactions? Obviously, valuation models are used in almost all transactions (I would assume). But if you are modeling a merger, there's going to be a pro-forma valuation. What about an IPO? A PIPE? What models do levfin groups use when structuring and executing debt financing?

What exactly is a PIPE? I understand it's a private investment in a public entity, but is this kind of like private equity, except the investment is for a minority stake in the company?

What models do advisors generally use? Would a sell-side advisor run a pro-forma model, or does the sell-side just worry about valuation modeling for their client and let the buy-side advisor run the pro-forma?

I'd love to take a look at any models you guys may be willing to share (including comps sheets). I am starting FT in the summer and have no IB experience and would like to familiarize myself with some of the standard models I may look at. I am the only FT hire that came in outside of the firm's summer analyst program, so I am trying to "catch up" a bit. If you're willing to send me a model, just leave a message here or PM me and I'll get you my email. Thanks for any insight.