If it is the latter do you allows Regulation A offerings for non-accredited investors?

See http://www.consumerfinance.gov/regulations/ability-to-repay-and-qualified-mortgage-standards-under-the-truth-in-lending-act-regulation-z/ Even if you are just renting with a pure option, send them to the RMLO for a written opinion.

Looks like you are fully amortizing the note, if so you'll have fewer issues.Not enough information to properly advise you on the financing.Read up on seller financing here and then post your transaction.You can often write up your sale contract with seller financing, amount financed, interest and loan term and settlement agent might do the note and deed of trust if they know the deal is exempt from new regulations, however they may not be doing that anymore, depends on the closing company.Next see a mortgage broker for assistance, but an attorney might be cheaper.Saying you don't have money for an attorney is almost like saying I cab afford to lose my house from doing it myself. :)

You can easily get stuck with a property that is no longer grandfathered from current zoning regulations if it has lost it's continuous use status(sat vacant for an extended period of time).

Much of it is universally applicable, but some of it is very U.S.A. specific - areas such as finance, regulation, and taxation are differ in Canada (and again dans la belle province).

This is a highly regulated business.  

As far as the non-dog animals, does the landlord have significant liability if the animal is not allowed due to HOA/local regulations? 

San Francisco has some regulations on mandatory improvements for soft story buildings and Los Angeles just came out with some proposed regulations that will require these buildings be reinforced

This happens because they know they will continue to do repeat business with you and the work environment comes with a lot less hassle vs dealing with a homeowner which can be challenging.

This is a brand new environment for me (blog/forum community and all).