One thing to note, that as SuiteScript 2.0 has now been available for a few years, very little attention is being paid to SuiteScript 1.0 anymore, so most recent articles and guides will likely use SuiteScript 2.0 for code examples.  When you say the company you work with is using SuiteScript 1.0, do you mean that they have demanded that no one use the newer API, or that the majority of their existing code is in the 1.0 API?  It is very common for companies to have both older 1.0 scripts, and newer 2.0 scripts.  While the two API versions cannot be used together in the same script, they can certainly live alongside each other within the same account.

One very good reference is the NetSuite Development Ebook, but it is focused on SuiteScript 2.0:  https://leanpub.com/netsuitedevelopment

Another good reference are the SuiteScript Cookbooks, but again they are focused on SuiteScript 2.0:  https://stoic.software/cookbooks/

I would strongly consider adopting the latest API, as its use is growing.  Spending time learning SuiteScript 1.0 may not be a good use of your time, as it is now considered a legacy API.  If you must use 1.0, try doing a web search for SuiteScript and filtering out any results from 2016 or later.  Prior to 2015 there was only SuiteScript 1.0, so all examples older than that will be using that version, even if they don’t say it explicitly.