Just extrapolating from the fact that you're only 19 years old and already have 60k saved up...Yes, go ahead and put 50% equity in if that's the factor that gets you the loan. 

I'd rather not do an entire cash-out refi because I have a much better rate on the property than I could get today.With a 70% LTV planning factor, I'd still have plenty of room for the cash I'm looking for to make the down payment (~125k).Thanks for any help/advice!

Fees are very reasonable, and they do a nice job of explaining the inputs.

The expense factor will be dictated by your line of work. 

Some like buying a tax lien can be done for as little as $500 (although easier said then done).You can wholesale properties of get a fee for being a bird dog and referring deals to other investors.

Because of my professional experience, we'd prefer that our properties be nearby so we can self-manage and save the 5-8% typical of property management fees, at least until our portfolio grows.

What are some factors to really  consider when analyzing mulitfamily properties.

The biggest factor will be the job relocation.

If the brokerage fee is owed to them if you buy any property, even without their assistance, then you owe that brokerage the full fee specified in your contract.

All three of these factors will check ok, nobody will call you out for mortgage fraud.