BP has worksheets you can use to calculate the "numbers" on rentals.

By my quick calculations, this will add about $450 to your monthly expenses, and reduce that $900/m CF down to around $450/m...$5400/yr. 

How do you calculate the maximum you can/want to afford?

A sewer break could mean 15k on top of what you are calculating.

We’d like to get a 3bd place (I work from home and there’s a chance we’ll have a second kid).Savings Rate –If we limit our housing expenses to $5k/month, I’m estimating that we’d be able to save approximately $80k (inclusive of retirement, college savings, and taxable) a year plus 100% of any bonus.As I said curious about anyone that has been in a similar position or more generally any thoughts on what you'd do in our position.

The cash. you take out is taxable but the rest of the gain is sheltered in the 1031.

If any, what financial calculations/formulas do you use as a real estate investor?

Primary residence gain is not taxable (to certain limits), so when you convert to investment property, you convert at a higher basis. 

Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.

In addition, your 30k cash-out is not taxable - but your sale profits are (even if tax-deferred through 1031).