You'll get a feel for the age of the neighborhoods, the vitality of the commercial buildings, the ease of location, the closeness to jobs.The markets you're describing are more linear, and usually have lower capital appreciation.

The 4% and 6% rates are just the names given to differentiate commercial and owner-occupied.The 6% rate is obviously significantly high, but it's fairly average nationally.

It includes HVAC filter and a few 'free' things (like one free lock out or something like that).

You have received some great recommendations and if you are yet to decide on an Investor friendly to work with, you can send me a DM and see if we are a good fit.I do provide free mentorship and a lot of free resources and connections to anyone I work with especially beginners like you. 

Interest income is interest income, unless you decided to roll some of the current cash into a self directed IRA at which point your interest income would be deferred for a later time and allow your funds to grow tax free.

You definitely wont get an app like that for free, so how much would you be willing to pay to a company to submit it for you, vs spending 10 minutes once a month to submit taxes? 

Start with BiggerPockets Ultimate Beginners Guide (free).

If you own (2) properties free and clear you could simply do a cash out refinance. 

Feel free to message me directly! 

For example, you could create a weighted structure where a percentage of profits is based on cash contributions, and another portion compensates for rehab or management efforts.Rent Payments and Tax-Free Profits:If you structure it as an owner-occupied property, the rent you pay could be shared proportionally, but tax-free gains on resale may only apply to your share, as you’d be the owner-occupant.