My situation does't feel like it would be particularly unique, but I have had a hard time finding a similar thread despite lots of searching.I am looking at duplex that I would like to buy, but both sides just renewed a one year lease last month.

If she complies no problem if she does not legally all you need to do is give notice not to renew her lease if the regulations allow.

The tenant is a jerk and I was not planning to renew his lease, but he beat me to the break-up first, damn! 

Germain provides for a due on sale clause trigger for residential leases longer than 3 years.I'm not an attorney, but you may run risks of a tenant showing equitable interest in long-term leases that may make them harder to evict if challenged.If the tenant wants long-term security, look to commercial leases for renewal clauses and, like everyone's saying, keep the term shorter.

However, what guarantees that the subsidy is going to be renewed in the next year?  

If they charge you hourly when anything goes wrong, charge you a fee for marketing and a fee for lease renewal, then the 10% appears to be for collecting each month.  

There are no other expenses except (1) the HOA/management fee paid my me of $80/mo (water, garbage, and grounds maintenance), and (2) the realtor processing fee of $200 paid upon each contract renewal.

While searching online I came across renew Indianapolis that is a land bank of a lot of the abandon houses in Indy.

Gives the opportunity to issue Notice of Non-Renewal instead of evicting.

Their Fee is $79/unit                                                                                                                 Tenant Placement Fee: None                                                                                                    Setup Fee:None                                                                                                                      Lease Renewal Fee: None                                                                                                        Maintenance Fee: NoneI just need a steady good cash flow