Are there online legal sites/apps that you can pay for this type of service?

A local real estate attorney can draft you a note and a security instrument (deed of trust, etc) for this lending arrangement.It would be good to have a loan servicing company handle calculating/collecting payment for a small fee (like how property management companies manage your rentals for a small fee).

I am specifically looking for companies with a proven track record of transparency and competitiveness in their fee structures and excellent customer service.

They will get a 1099 for the deficiency; in the case of a deed in lieu it's generally the servicers FMV - payoff.

From this you need to take your debt service (1500 - 1700/mth) and set-aside a reserve for Emergencies/CAPEx ($300 - $600/mth).  

We run Call Porter an answering service for investors (and are also buy and hold, wholesale, and flip investors) and get to chat with clients about what is working/not working all the time.

They are full service and do property cleanups with their list of go-to subs at a 10% management on renovations.

Generally I use other companies that provide the service because you more easily tailor the type criteria you are looking for. 

I think buying is a solid choice as long as you make some good contacts while your hear, most importantly a good property manager but also try to find a good handyman for service calls, a good cleaner, good yard person, ect.  

I work for the Dept. of Human Services in the City & County of San Francisco.