Correct train and Questions

Different trains use the same track, and may only be in the station for a few minutes. At the head of the track there will be a sign with the train number and destination, some intermediate stops, along with the departure time. The train should also have a destination sign on on the front of the engine and signage beside each car door. as well. Make sure you pick a car with the correct class of ticket- first or second. Some trains may split off at certain points, so double check the destination beside the car door before boarding.

If going to Rothenberg ODT, you'll be changing trains a couple of times. Make sure you know where you have to change.

I land at 9am I can purchase a Bayern ticket, jump on the first S-1 or
S-8 to Munich Hbf and wait for the next train correct.

Correct.

At Munich Hbf, there will be a digital display over the platform with the train number, destination, and scheduled time. There will also be a clock showing the current time. The display will show the next train scheduled to leave from that platform. If the train is even 5 minutes late, the sign will say that too - "5 min verspätet". Since your train originates in Munich, it will probably not be late, and it will probably be sitting there for a while. But just to be sure, check the destination card next to the door.

And, by the way, you said "I am standing at track 4 at 12am." 12am is indistinct. Is it noon or midnight? (Most people would say midnight.) That's why the European say 12:00 or 24:00 (or 00:00). Incidentally, in the US, according to the National Bureau of Standards, there is no such thing as 12 o'clock (am or pm), It is midnight or noon, officially.

What I need to know is I am standing at track 4 at 12am and I need the RE-1711 to Munich, when a train pulls in or is all ready there, How do confirm this is the correct train to be on, Isn't it posted on each car?

The trains final destination may be on the front of the train. This is more common on small local trains.
ICE trains also have a small video screen beside the door..
But the main thing to watch for is the platform indicator, which hangs above the platform showing the train for that platform.
Photo: http://tirol-bahnbilder.startbilder.de/1024/zugzielanzeiger-fuer-ice-503-nach-235455.jpg
Another Photo: https://bilder.t-online.de/b/72/54/16/74/id_72541674/610/tid_da/viele-verspaetungen-deutsche-bahn-erreicht-eigene-puenktlichkeits-ziele-2014-nicht-ganz.jpg
As you can see, it has platform number, train number,, train departure time, main stops and even shows where the 1st and 2nd class coaches will be. The coaches will be labelled "1" and "2".
The train in the second photo (RE 11 from platform 8), has a "Verspätung circa 130 minutes" (delay of approx 130 minutes). This is very unusual. I got this photo from a newspaper article about delayed trains, probably the worst case they had.

I can purchase a Bayern ticket, jump on the first S-1 or S-8 to Munich Hbf and wait for the next train correct.

Correct.

When in doubt, just ask the conductor if your train is now boarding. More than once, this saved my bacon from making a mistake and despite all the great advice above as well as being alert/sober, etc.

Agree with Bruce. When in doubt ask the conductor before you board. Or any of the other people waiting to board.

Yes, once you have your Bayern Ticket, write the names of all travelers in ink on the back of the ticket and you can take the next S-Bahn to Munich Hbf.

The itinerary you site has some fast changes required, so be prepared. At Treuchtlingen, you only have 5 minutes to get from Track 2 to Track 7. That means being prepared by the door with your luggage when the train pulls into the station. Push the button as soon as the train stops to open the door and go down the stairway to the cross-over tunnel and walk about 100 feet to Track 7 stairway and up and onto the train. This train originates in Treuchtlingen, so it will be sitting there waiting.

Same deal at Steinach, going from Track 2 to Track 5. Again the train to Rothenburg originates in Steinach, but everyone boarding it is going to Rothenburg, so it generally will hold until all the slowpokes are on board.

What I need to know is I am standing at track 4 at 12am and I need the RE-1711 to Munich, when a train pulls in or is all ready there, How do confirm this is the correct train to be on, Isn't it posted on each car?

When in doubt, ask the conductor standing by the train "Nach (destination)?"

from the Munich airport to Rothenburg ob der tauber leaves at 11:24-15:50 I land at 9am I can purchase a Bayern ticket, jump on the first S-1 or S-8 to Munich Hbf and wait for the next train correct.

Since you are travelling on a Bayern ticket you can take any train as soon as you are through immigration and customs. If your flight is on time you should make the 10:24 S8 easily and arrive in Rothenburg by 14:50.

Usually the regional trains from Munich Hbf to Nürnberg (you leave that train in Treuchtlingen) +) sit in the station 20 min before departure. Those are double deckers and the destination is indicated on each car. At the beginning of the platform (for the connection suggested above: #20, for your original connection: #24) there is an electronic train indicator displaying train number and infos on possible delays. If there are problems, there is a DB info point just a few steps away. In Treuchtlingen trains in your direction always leave from track #7; terminus is Würzburg but you transfer in Steinach to the tiny Rothenburg shuttle, which leaves always from track #5.

+) Note: As said above, the destination of the first train of the connection selected by you and the connection suggested above is Nürnberg but you transfer from that train to another train in Treuchtlingen. Now, there are also trains from Munich to Treuchtlingen going via Augsburg from other platforms. Don't take one of those and make sure that train number and track number match.

To determine if I got the right train once I am waiting on the platform, I listen to the announcements over the PA system, (to hear whether the train is late or not), look at the electronic board for Gleis # and the time, and the number of the train pulling in. Plus, as the train is pulling in, I also look at the terminus of the train I want, which tells me the direction it is going.