I have my financial life together so I've only had amazing experiences with the major banks, they seek me out offering assistance and services for deals.

I'm fairly new to note investing (and real estate investing in general) and am not accredited, however I have worked in investments (stocks, bonds, mutual funds, etc) for 6 years and actively invest in those arenas and am a CPA, so I'm pretty comfortable with financials/investments/risk/etc.

When it's time to deal with an attorney I will certainly seek the proper channels and move forward accordingly.

Shouldn’t be too bad.However, converting the Duplex to a four plex is a much bigger deal, I would seek out some more specific advice to your location before pulling the trigger.

I believe @Michael Plaks is based out of Houston and is very active on the forum with answering/helping with tax questions.For CPAs, I'd recommend prioritizing someone who is an expert in real estate over someone local (and if you find one that's both- great!).

Met an investor who is seeking private lending and also partners to go in on multi family deal(s).

I´m trying to get a sense of what makes a good deal that would justify moving on towards the next step of seeking out a cash buyer.

Your situation depends on your involvement, your entity selection, and lots of other factors that preclude an informed opinion.3) You didn't ask, but I offer that you should not take or act on any legal, regulatory, or financial advice on a free forum and always seek a professional opinion or two.  

A good camera or a new smartphone with a cutting-edge camera may trump the need for a laptop, but if you are seeking a laptop I personally like the Microsoft Surface Book - its lightweight, its got a touchscreen, it got a good battery and decent entry point for a decent machine. 

Suggest you seek your advice from a CPA based on your current tax.