One of the units was currently rented for $3300, with an accompanying lease and last month's rent deposit collected at close.

Your daughter's friend is still accumulating assets and if she buys with an FHA loan there will not be a lot of equity thus will be judgement proof.

And if we mail it how do we properly collect a certificate of service that will provide proof in court that we delivered the notice on time.Can we hire someone to legally serve the Notice?

It's funny, when I was a kid I would collect unwanted tires and sell them to a recycler for $3 each.

However, screening of the spouse revealed debt, collections, no source of income, etc. - I would never accept that person alone.

Just need to find one that could be a proof of concept. 

The con of starting now is that the investment properties value will dip shortly after you purchase it.In my opinion, the pro of starting now is building a network, getting my feet wet in real estate, and being even more prepared to save up and buy up property when the market dips. 

The fees do not go towards the deposit, because we don't collect the fees - the company doing the check (we use MySmartMove) collects the fees.

Should I reduce the offer price and not collect monthly rent but ask that they pay utilities and other stuff like cable, etc?  

Delay could be used in damages...assuming the Seller is not judgment proof.