Two Wiring Questions + Derailments

[clickmatch]

I tried searching around, but these are issues that were difficult to hone down to a short search term. So I figured I'd just pose them.

#1: I'm wiring some Super O, so for me it was easier in a turnout to just remove the center pin and run the hot wire back to a SPST switch so it can be interrupted and turned on with a switch, which goes to the switch then into the bus on the main pole. (Position A). This means the common rail is still "active" and has track current running through it. The question is,  does this pose any problems for a loco sitting on the track to have the outer rail getting juice but the center rail is deactivated? Are there any issues in global wiring terms that will cause issue? THe remediation would be to separate the outer rails, and change it to a DPST switch. What would you do?

#2: I have an old loco in need of servicing and oiling. But I had my deisel crap out on me (which I later fixed, some old solder finally gave up and the green wire came off). But for testing purposes I put a steam on there (Forget the # I'll check when I go home). WHat happened was I saw "burning" on the center rail where it was, after it moved by. Like a black soot was on the surface. I was alarmed and took it off and now I'm wondering if it was the loco. I have the track secured by metal T-pins, and my first instinct was that a pin was touching the track and grounding it, but I'm not sure that logic is even right. So the question is, will servicing make this go away, or do I have some kind of wiring issue?

#3: My switch track causes my loco to derail (#112's I believe). This happens most of the time, and much more likely in reverse. This was using a deisel with magnetraction. Are there any resources that explain how to remediate this, or modify/clean/adjust the switch so it operates more smoothly? I did not test with a regular steam loco because of what happened in question 2... I need to clean one up soon, but I've been trying to get all the track laid before I went back to servicing.

Whew... sorry for being long winded. Thanks!

[clickmatch]

Update... #2 involves a Lionel 646 Loco.

[lionelsoni]

The SPST switch to the center rail is the way to go.  There is not harm at all in having the outside rails still connected.  No current is flowing to your locomotive if the center rail is open.  Its much like the case of a bird perched on a power line.  He's perfectly safe because he's touching only one wire.