The costs of selling on a real estate contract, is essentially no different than financing thru a lender, except the lender costs.
There is 1.78% excise tax due by the seller...
there are title and escrow fees . You can get estimates online at Clark County Title,
There are minimal recording fees etc. very typical of any transaction
The property taxes will be pre-paid to the next collection date. Whether those taxes are current makes a difference, and the buyer pays in advance, at closing from the date of closing.
IF there is an underlying mortgage, there may be a "due on sale" clause, which you need to understand the possible ramifications of your plan.
If you utilize a 3rd party note service company.(I recommend this)..the set up fee is 125.00 and the monthly from 7-14/mo,
this records the payments, provides the interest paid statement for end of year taxes, and generally a good idea..even with family. Your payment goes to a 3rd party servicer, then to the bank.
The title company will create a HUD SETTLEMENT STATEMENT for you in advance, so you each know your respective costs, fees.
If you need further assistance, with your agreement, note or real estate contracts... Drop me a note. I can assist you with the preparations, but some legal council is advised.