Cashflow, Vacancy, late fees?

[Scott Titus]

Further Analyzing rental property. Purchase price $50-60k. Low income area, not a warzone. Not counting on appreciation. Rehab 15K. 

Here's my #'s

Home rents for $900 per month (5-10% below MR). Vac 10% ($90), maintenance 5%($45), capex 5% ($45), property tax $140, insurance $91, property mngt 10% ($90). $501 + Mortgage $235 (20% down on 60k loan) = Total expenses $736

Monthly Cash flow $164 ($1968 yr)

Cash to close (3% closing + rehab + downpayment) $28,800

Coc 6.8% ( 11% if rented @ market rent)

Equity- $38K

Couple questions I hope to clear up:

Assuming rehab and ARV are spot on....

1. Are my numbers too conservative, making me pass on rentals that can really pay off

2. If I assume a high vacancy, can I also assume at least 5 out of 11 months incurs a 5% late fee each yr? ( $225 yr) 

3. Can I calculate pet deposit $200 or $25 month pet service in analysis. Or just a bonus assuming I will have to change the carpets yearly anyway..

Thanks.