After the owner paid for the license application, I worked with the county to get the STR license approved under the owner's name with me as the manager.

Will they pay $500, and $100 will be paid to me at escrow?

Generally will cost you about one month's rent, and some of that amount may get paid from your listing broker to the tenant's broker that brought the tenant resulting in a successful lease agreement (this benefits you because you are essentially offering financial compensation to other agents that represent who you need: tenants!)

I paid a licensed and insured company, who is pretty big in our area, to replace it. 

Someone who paid $200,000 for a property 10 years ago, that is worth $600,000 today, might be perfectly content with $150 per night from now own.

. - Construction is more expensive.

(Works better than expensive Scrub brushes.3.

If those cards aren’t good then I’d just look through your cards and decide how many I was going to keep and make sure my logic was solid and if I had debt on them work to get it paid off and then like you said just let the rest die off from lack of use!

Yes you're getting the loan paid down by the tenants and hopefully the property appreciates in that time.

What if your friend had 3-7 paid off rental properties netting $2,000 per month each?