In fact it's a rather lovely LTV rate for the lending institution, very secure for them.For a primary residence I wouldn't monkey around with the value play too much. 

If your plan is to maintain this home as a primary residence for a few years and then convert it to a rental portfolio asset, leave it alone!  

that I own are within 1.5 miles of my primary residence in Oak Park, and I could walk to each of them.  

Cant say much on taxes as you havent said if this is your primary residence or a rental property now.

A 4-plex is not a commercial loan as it will be zone residential. 5-uits and more are considered commercial, but to answer your question the primary difference between the two loans is that a residential loan is based on your income to qualify for the loan where a commercial loan is based on the property's income.

On my primary residence purchase mortgage I was asked to explain why a particular address showed up on my credit report.

@Kevin AllenIf you are talking about a multi-unit property (i.e. a 16-unit apartment) there is no expectation of privacy in the common areas of the property - including the grounds.If the property is a residential property (SFH, townhouse/duplex, etc) and you have not established in the lease that you would be retaining access to a portion of the property (garage, out-building, grounds) or that you would be providing an ongoing service (yard work, snow removal), it is reasonable for the tenant to expect quite enjoyment of the entire premises.  

Is it wiser to purchase a primary dwelling and then after we save up again purchase an investment property or would it be more prudent to purchase an investment property and continue renting until the income from the new property accumulates?  

Ill be making several trips down this summer to find a primary residence, and making the move in August.

From a dealmaker/promoter point of view the primary value center for a marketplace is access to investor eyeballs.