Hi @sed6! I really like your design! Clean and elegant.
Now that you have your design, you can set about making it motorized and runnable on the track.
In your last picture which showcases the skirting on the monorail in correlation with the track, there doesn't appear to much clearance if any.
This is a problem because in order for the monorail to run along the track properly, your going to need to use guiders. You can see them being used in red on this motor bogie.
Depending on where the guiders are located underneath the monorail in correlation with the distance in length between the guiders will dictate what the length and/or design of the skirting can be. (Note: I usually don't have the skirting on my monorails go pass the wheels because if my monorail has the ability to take very tight curves, it can do that. Unlike if the skirting went past the wheels and partially covered the rail to whatever extent in which case it may rub against the rail. Does it look as good when the skirting doesn't cover the wheels and rail? No, but it would make the process of designing your monorail much easier. :-) )
Back to the discussion of guiders, the max length in distance between the guiders will depend on what the smallest curve radius is that you'll intend to use your monorail on. The max length will be when if the guiders are spread apart any further, it will start to create resistance and drag and negatively affect the monorail's performance.
Another thing that creates a lot of resistance and is often overlooked is the distance between the wheels. The farther they are apart, the greater the resistance. Imagine trying to turn while riding a bicycle whose front wheel can't turn. The only way you could turn is to drag the front wheel across the pavement in the direction you wish to turn. It's the same thing happening with the monorail when the wheels are to far apart. Also like the bike, the solution is the same. I personally recommend that each monorail car should have one fixed wheel* [motorized or unmotorized (a wheel that doesn't turn)*], and one bogie wheel that turns.
There are different ways to design a bogie wheel. I recommend a design similar to one made by @FiliusRucilo or something like it. Here's a picture of one of his designs.
And finally, motorization. I definitely recommend starting out using small wheels. They'll allow more room for when you're working with the gearing. As for worm gears, I've never used them, but I'd definitely give it a shot if I were you.
I recommend you keep your gearing low. I personally prefer a slow & strong monorail vs a semi-fast & semi-weak monorail, but depending on how smoothly your monorail runs will probably be the deciding point. Both my first monorail design and my suspended monorail design can run very smoothly even on the slowest speed setting when using the seven speed remote control. I used this as somewhat of a test when I was designing the monorails.
I hope this will be helpful. Let me know there's anything in specific you'd be wondering about.