Welcome to TE!
The Dash is the flat-bar bike. Do you want a flat-bar (like what you have now)? If you want to do a century, I would suggest you look at the Avail models, because the drop bars give you more hand positions.

Between the 5 and the 3, go with the 3. The 5 is Shimano 2300 with a Sora rear derailleur. The 3 is full Sora, and the new Sora gets you the paddle shifter rather than the thumb trigger on earlier Sora or 2300. The paddle shifter (like the ones on the higher-level componentry) gives you the ability to shift from the drops.

My Avail 3 is actually the equivalent of the current 5 (I bought it the spring after the economy tanked, so they were trying HARD to meet a price point), and I wish I'd saved my money and sprung for the Avail 1 (105).

For $1000, though, you should be able to get Tiagra, which is nicer. See if you can find a Defy 2. Try a whole bunch of bikes if you can. Take a road trip.