Hello,
I have been into Lionel Trains my whole life and my first set (which I still have) was bought by my Dad the week I was born - 65 years ago! My layouts have grown over the years and I now have a dedicated room for my trains and layout which is now fairly large. It has 5 separate track loops and I am now in the process of wiring it up. I actually built this layout 22 years ago but got sidetracked and never wired it up or completed it. For 22 years they basically sat idle! Well, I'm back into it now - bigger than ever!

About 1/3 of my collection is post war, a bunch is from the 70's & 80's and I have bought a lot of Command Control Locos from the late 90's and early 2000's. I am now intergrading in TMCC equipment (the original version)  and it's been somewhat confusing for someone who has up until now only operated conventional Lionel's. Since it's been a while I'm a bit rusty and will definitely have many questions for those here who can hopefully offer up advise and direction so thank you in advance!

My first & second question's are .......

On one of my conventional track loops I have 4 spurs with 4 switches. I'd like to isolate the spurs so I am able to park loco's on them without lights and smoke going. I know I can use toggle switches to cut off the middle + rail, but am I correct in not bothering to also cut the ground rails? I can not think of any reason to, but don't want to do it incorrectly. So if I only use a SPST switch am I good to go?

I am also using 5 separate transformers. Am I correct in assuming I should ground them all to one another via a common ground block?

Again, thanks in advance.