My advice is put it on as many sites as possible and put strong discounts on extended stays and you can attract both simultaneously.

I've personally transacted on a house +ADU + JADU that was rented to three separate tenants.If I am taking the risk of breaking a deed restriction, I expect the associated discount. 

I’m looking to purchase a commercial office building that has been heavily discounted due to pcb in soil.

If it's 3 or more months I will give a discount for prepayment of total rent $50 per month.

Not every seller wants to use a realtor, not every seller wants to sell their house at a discount.

Do I discount the rent from the escrow automatically?

I would go with a company who has multiple properties under management (ideally over 500 to really get the benefits a scale, think cheaper maintenance visits, experience placing tenants, lots of investor experience, ability to find deals within the brokerage, massive marketing channels for properties, systems in place to handle problems, experience handling a massive amount of problems, discounts for bringing multiple properties to manage).Also, make sure your property manager is motivated, experienced, and growing! 

However, it would be a 1-time reimbursement/discount, not a permanent one. 

There are no magic discounts for "flippers" or "investors" .

For example, wholesalers are great because generally their properties are off market and you get them at discounted prices.