Uma, full fare tickets (€81) on German Rail are open tickets, that is, they can be used on any train, and the period of validity ends at the end of the day following your start of travel. So, with a full fare ticket, you could stop at all those places, as you desired, as long as you completed the trip by the end of the next day.
HOWEVER, it looks like you are planning to use one way of a round trip SparPreis fare (€116). Those tickets, like most discounted fares, are only valid for the trains you book. You could make those stops, but you would have to build them (2 max, I think) into your booking. You could not schedule a two hour stopover, and stay longer.
Also, what are you going to do about start time? If you buy the ticket for just after your flight's scheduled arrival time, and the flight is late, you would miss your train, and the tickets are non-refundable. You will have to build in a time buffer to account for any flight delays.