David Liverett says:

First off, welcome (or welcome back, rather) to the hobby!

Second, I have used all manor of turnouts with equally varying levels of success. In HO, I Ted to gravitate towards Atlas Customline switches. Even the insulated frog version is very good. My layout is DCC N scale, and I run Atlas flex track with Peco Insulfrog switches. My GP30 and GP38-2/40-2 etc usually have no issues, and of course SD40-2 or Dash-9 locomotives run perfectly fine with them, but a SW9 or SW1200 may have some issues if by themselves. I have a pair of SW1200 locomotives that I hardwired together electrically so all 8 axles across both locomotives feed booth locomotives to negate that problem. Peco makes an electr-frog also, but I have no experience with them, so I cannot attest to their operation characteristics.

3rd, yes! Most people, myself included, started off DC and when they went bigger or decided they wanted sound or multiple trains at once change over to DCC. A well made, well wired DC layout can be swapped for DCC in seconds, just by changing out the power packs. Also, a bonus for you is that you can run both at the same time. With DC track running a decoder equipped locomotive, when you give throttle to it, it won’t start moving till about 3/8ths to half power. The sound will start up first, then the engine will start moving. Vice-versa, with DCC track and DC locomotive, the signal going thru the tracks will make the DC motor inside the model hum, or squeal even, depending on the engine. You run these DC engines on DCC address “0.” The hum is the pulse-width modulation, or pwm. Basically, what is going on is that at stop, the command station (power packs are called command stations in DCC) sends a forward pulse quickly followed by a backwards pulse, which makes the motor inside the model shake back and forth super fast, and will heat it up. When you send commands to move the model, the command station sends more commands one direction than it does the other direction, making the motor overpower the “hum” in that direction, moving the model.

You can run DC locomotives on a DCC track all day long and, in theory, should be fine, as long as you are moving at 50% or higher power. But a general rule of thumb is an hour max, then give it a good 20 minute rest off the tracks. Also, anything made in the last 5 or 10 years is most likely DCC ready, so swapping the DC plug for a decoder is pretty simple.

One last thing, “DCC Ready” means that a locomotive is wired for DCC, but not decoder equipped. “DCC and Sound Ready” also means wired for DCC, but also has a milled out hole for a speaker, but still no decoder or speaker, just ready for you to put one in. It isn’t very common except Kato N scale, but you can find brand new from the manufacturer “DCC Equipped” models that have DCC but no sound. Most of the time, if the manufacturer is going to pre-install DCC, it will have sound too.

If you buy new, look at the box, it will say one of those four options. Just remember if it says “Ready,” then you need to do the decoder install. If it says “Equipped,” it already has it.

If you buy used, ask to see a video of it running if online or if at a show, ask if you can test it. Most people that bring layouts will gladly put it on and try it out for you. If the seller will not let you test it out before buying, they are probably selling snake oil. Pass on the item. I just watched a YT video where a guy bought a $400 Lionel O Scale that supposedly had Legacy Sound and everything in it, wouldn’t let the guy test it out, and when he got home, it was gutted. Didn’t even have motors to move the model with. Just wheels, a roller or a dummy engine. I felt so bad for the guy.

I know this is way more than what you originally asked, but I like to help out the best I can! Another really good resource I would recommend is to look for a local club to join.

Good luck, and once again, welcome!