Basically you are on the right track.
I would question the reasoning for a pre wet, unless you really do have a temperature problem. However you are going to develop at room temperature, more or less, so I don't see the reasoning.
The RA4 colour process in every commercial machine, does not do a pre wet. I now process in a roller transport machine, it doesn't have a pre wet. When I developed in drums I didn't use a pre wet, as it isn't in the official processing instructions, I never had a problem, ever!
I have done one shot processing and ½ shot processing in drums, let me explain. Say your drum requires 50ml for an 8x10" print you can use just 50ml, or be generous and use 60ml to ensure you cover the paper. What I found was a more consistent process with drum processing, was to use a fair amount of developer. I would use 150 ml for an 8x10" paper, at the end of the cycle I would dispose of 75ml and add 75ml of fresh developer for the next print. By doing this I maintained exceptional colour consistency and saturation from print to print. This consistency is something that is reasonably important and slightly hard to do, if you are running with minimum chemicals in a drum. I know this from personal experience.
You do have to ensure that you have enough active developer to process the square area of paper, do keep that in mind.
There is no stabiliser in RA4, at least I have never heard of it.
With drum processing I found that a stop bath was a very good idea for consistency, followed by two quick 30 sec washes.
Once the print has been bleached and fixed (blix) I used to do one quick 30 second wash in the drum, then take it out put it into a tray and wash it the same as B&W prints.
You can dry the drum whilst the print is washing.
I found I never needed the starter after I forgot to use it once, never used it after that.
A possible route for colour balancing, is to photograph a colour chart, if you have one or can borrow one, in mid morning or mid afternoon clear daylight.
Then in the darkroom, work your way to getting a reasonable white and grey and the other colours as well.
I suggest a colour chart instead of a grey card, you'll never get an accurate representation of a grey card from a colour paper.
Mick.