So there was really no reasoning with him, he seriously believes he doesn't have to pay taxes.My question is is there any way I can ensure to be in the first position to buy the tax certificate so I don't lose the property?

Or it could be the other way, and he could care less about the interest rate and he is just spouting off monthly figures that he "thinks sound good," and they might be even lower interest than we expect..

If so, figure on losing about 20%-30% through collections losses/leaks.  

Also, with spring coming, I may lose out on a longer term tenant.Opinions on whether I should take these tenants( assuming regular qualifications are met)? 

Doesn't sound like much $$ to lose, but I have heard that they spend the majority of the time "up-selling" you on the next big event or other "stuff."

It's all losing large amounts of money to be popular.

They know they'll lose money if they go below that so that is your 'bottom end'. 

You don't want to guess on a repair cost, and blow your profits or worse, lose money! 

Offer any more and you lose money. 

But once they learn how much work goes into that, many will lose their ambition quickly.