train tickets in Germany

Airport to downtown would just be an S-Bahn or U-Bahn ticket, starting point for the rest would be point to point, if in the same region, there may be some day passes if you can depart after 9:00 AM, maybe a deal for three. For the DBahn site, they should walk you through their deals, buyt some of the regional things you will need to search separately

Saver tickets, nonrefundable (can be refunded with a 19 EUR fee up to 24 hours in advance). Frankfurt to Rothenburg and Rothenburg to Heidelberg are 67 EUR for a group of 3 for both trips. Frankfurt airport to/from Frankfurt city center is a local RMV ticket, you buy out of a ticket vending machine. 4.80 EUR per person each way, or you could buy a group day ticket for 16.40 EUR and use the Frankfurt transit system for the rest of the day.

I think the Bahn site is very straight forward. They can't show local network tickets because they are not allowed to sell them on-line.

What is a "Bahn ticket"? Is that the same as a point-point ticket?

I don't find the Bahn site at all confusing, but it does give you a spectrum of tickets to choose from, depending on the type of trains used, so you have to do a little comparative analysis.

Frankfurt Hbf - Rothenburg odT: If you are willing to commit in advance to a specific train, you can make the trip in 2H40 for 63€ with an advance purchase Savings Fare ticket. For 60€, you can make the trip with a Quer durchs Land Ticket in 3H19M with no train commitment.

Rothenburg-Heidelberg: 2½ hrs, 67€ with a train commitment and an advance purchase ticket. 3H15 and 60€ with a QdLT ticket and no train commitment.

The other two trips are short; I would just use P-P tickets.

So it's kind of six of one, half dozen of the other. Big question is are you willing to commit to a specific train for a small difference in timel.