1. What is the color of the paraments? LSB prescribes green for pre-Lent; black or violet for Ash Wednesday; violet from Invocabit through Judica and either violet or scarlet for Holy Week, with the possibility of white for Maundy Thursday.
2. What preface do we use for Pre-Lent? LSB prescribes Epiphany's preface.
3. What changes in the Divine Service? From Septuagesima onward, the Alleluia is replaced by the Tract. The Gloria in Excelsis does not disappear until Ash Wednesday. The Gloria Patri is dropped from Judica forward.
4. What about the Creed? We use the Apostles' Creed for the penitential seasons so that our parish doesn't completely forget it - but this is an innovation. The traditional creed for the Eucharist is the Nicene. LSB doesn't prescribe the one over the other, but provides either, giving the Nicene first.
5. Which post-communion collect is appropriate during Pre-Lent and Lent? I suggest the first one: "We give thanks to You, almighty God..." At St. Paul's we reserve the second prayer ("O God the Father...") for Advent through Transfiguration.
6. How can I help the congregation understand the purpose of Pre-Lent? Use the analogy of Lent as a trip back to the Baptismal font (at the Easter Vigil) - a return to the life given us there. Pre-Lent is the time to make preparation for that trip. It's the time to decide how you will observe the fast (something each of you should discuss with your confessor - and yes, each of you should have a confessor!).