But now that it's a public safety concern, can we legally remove all the trash they left out on their driveway? 

With the market the way it it, all of the really good contractors are super busy and usually outside my budget so you are left with people who aren't really concerned with the timeline or the quality because they have 10 more investors calling them to walk properties.

A normal purchase will allow you an option period to have a full inspection which includes looking behind the electrical panel , under the home, in the attic etc. from there if your inspector sees something of concern they will include that on your report and from there you can get second opinions from a plumber, electrician etc. this is always my biggest concern for first time investors who buy from wholesalers - no inspection, all cash, many times inaccurate repair and ARV figures and no one in your corner.

My biggest concern is I already have a good deal of debt from college, about 100k, is that something I should get rid of before investing?

The experience you have leasing up and managing your current properties is the same thing you will be doing in larger multifamily, so I do not think you should be concerned about having enough experience.

Full transparency, my wife is concerned we're going to be "downgrading" substantially. (2) any thoughts on what are some of the areas outside SF which lend themselves nicely to what we are trying to accomplish?

It is an older building and has a boiler, which has me concerned.

If it is impossible for you to look at the property prior to purchasing, you MUST have trusted partners that can point out repairs/concerns and estimate (in dollar terms) the remediation plan.  

If your concern is staying close to to your grandfather, then stay close to him in your house hack.

I'm not concerned with the current LTV, the proposed CLTV, any market adjustments, the property's current value, etc.