I really think you need to get familiar (quickly) with the transportation system in Frankfurt.
There is a station at the airport, for regional trains (RE/RB) and S-Bahn's, called the Regionalbahnhof. Although some people believe it is under Terminal 1, it is actually under the building across the access road from Terminal 1. You come up escalators from the Regionalbahnhof into the large rooms in T1 where the check-in counters are located, hence the misconception.
There is another station, the Fernbahnhof, for long distance trains (ICE/IC/EC). It's located beyond the building across from Terminal 1, and has a covered access bridge over the autobahn. Unless you go a ways from Frankfurt, you won't be needing the Fernbahnhof.
From the Regionalbahnhof, S-Bahns (and a few regional trains) go into the main station in downtown Frankfurt, the Hauptbahnhof (abbreviated Hbf), in about 13 minutes. Your hotel is just a few blocks from the Hbf.
So, if you are flying into FRA, you'll need to find the Regionalbahnhof and take one of the trains to the Frankfurt Hbf, then walk or take a taxi to your hotel. Regional trains arrive at the Hbf at ground level; most S-Bahn pass through the underground S-Bahn station.
For the rest of the time, until you fly out of Frankfurt, you won't need the airport stations. The Frankfurt Hbf is a hub for trains that go all over Germany, including, with a likely connection in Mainz Hbf, to Bacharach and St. Goar.