I know that Bachmann's standard On30 E-Z track remote turnout mimics the standard 18" radius curve, but how about the #5 and #6 remote turnouts? Are their "curves" also 18" and if so, how do I manage a turnout for a loco that won't take a curve that tight? Also, if the #5 and #6 remote turnouts are electrically gapped, do I need to "ungap" them if I am running a wide-open DCC system? Finally, I can use DC-powered remote turnouts and crossovers on the same layout where I use DCC technology to control the locos, right?
Take a look at the clickable link below. It gives the important radii for numbered turnouts. Most manufacturers' products approximate these recommended dimensions.
As you are already aware, a "radius turnout" has a constant radius through the curved portion of the turnout. This makes track planning easy and works well with fixed radius sectional track. Numbered turnouts, on the other hand, take up more room and generally do not exactly replace other sections of track. But their curves approximate spiral easements which definitely enhances smooth running.
Bachmann does have decoder-equipped turnouts for control by DCC
You can control the standard turnouts with AC power while using DCC on the tracks.
You gap rails for turnouts (depending on powered or no powered frog and turnout type – all live or power-routing) per wiring required by the track plan regardless if you are using DC or DCC. Using the old technique of DC Cab Control (block wiring) requires more rail gaps and electrical switches.