is it possible to embed the form into another webpage and pre-fill data based on external information?

Additionally, is it possible to embed the form into another webpage and pre-fill data based on external information, such as an account name/number?

Generally, iframe embedded forms can be populated via URL parameters same as you mentioned. Here is how to get the embed code: Getting-the-Form-iFrame-Code

But, there may be some restrictions for web site platforms. For example, if a web site platform puts our embed codes into their own iframe, pre-population will not work.

Here's an example of a basic website where I embedded the form using iframe: 

https://shots.jotform.com/johnrex/2406378.html?name[first]=Rex&name[last]=Test&email=john@example.com 

GUIDE: Prepopulating-Fields-to-Your-JotForm-via-URL-Parameters