The kilt, socks and flashes are to my opinion very well color coordinated. Couldn’t be better. Absolutely perfect.

You seem to worry a little bit about your kilt being casual. Don't. Who of your collegues, do you think, should be able to tell the difference between your very good looking casual kilt and an 8 yard hand sewn master piece which they don’t even have to compare it with?

Regarding ‘your about waist level’, I’m a little bit more in doubt. And that’s mainly because of the waist coat. If you normally are wearing one, it is OK, but if you never do, why with the kilt?
Here cultural differences might play a role. In Denmark, where I live, men wearing waist coats to job (or at all) have since the 90s or earlier become as seldom as are men in kilts. It might be quite the opposite in your country, however.

I prefer the light colored shirt over the dark blue one, especially together with the dark grey waist coat. Again that is my opinion.

If it is normal to wear a tie to job (in Denmark it is no longer that common, not even among general managers - unless they are to meet people from abroad), do it.
By all means, if you’re going to wear the waist coat, wear a tie, too. A waist coat and a shirt without a tie look (IMHO) wrong.

Most important thing; whatever you chose to wear, feel confident and secure. With all the combinations you have shown us, you should be able to!

Greg