Tax lien sales..

So we have this idea to create some rental properties. Going through the whole plan , things pan out well with a projected 5 year outcome.
Basically... in 5 years, all of our purchased properties will come out of the red if not sooner.

We are looking at foreclosed properties and properties up for sale due to back taxes.

I was wondering if anyone has had experience in purchasing one of those properties? Granted, the steps look very easy and signing up to be able to participate in the auctions is a snap. Done.. ready.

I see a lot of properties with the clause that the minimal bid accepted is X amount of dollars. ( for sake of example lets say 3,000 )

So this 3,000 bid is the minimal the county will take. BUT.... the property has been put into the bidding several years in a row with no sales. Im wondering if properties like that would go for less than the minimal bid... maybe there is a magic percentage of the minimal bid they would accept?
I know the only way to find out is to DO it, but hey.. never hurts to ask right.

What if the land value was appraised several years ago and the land and property has since decayed? I can not find a place or site that tells me how to deal with issues like that.
When you read through the break downs of the properties it tells you exactly what the land value is, property value and even JUNK value.. ( yeah. the junk left is added in . Go figure..)

So, if you have had to have YOUR property appraised, and / or have the appraisal challenged or changed, how easy is that? Who do you contact? Tax assessor? County? city?

Tons of small questions and it seems that I am hitting a wall on how to find answers for the simple stuff like that..