A couple of points.

1) You look great as is, so there is really no need to change anything unless you just want to.

2) Regarding the choice of the Argyle jacket over the Prince Charlie, you can read a variety of opinions posted here already, from applause that you chose to wear one for a black tie event, to criticism that "three button waistcoats" or "diced hose" should only be worn with a PC. These are only opinions, of course, but please understand that it is perfectly correct to wear a black Argyle jacket to a black tie affair, and that includes a three-button waistcoat and diced hose if you so choose.

3) I agree that diced or Argyle hose would be a step-up for formal wear, but there is nothing wrong with solid hose in lieu of those. I disagree that Argyle-topped hose would be another option. I'm a big fan of patterned cuffs on hose for day wear, but I cannot recall ever seeing them worn traditionally with evening wear. So I would stick with solid if you cannot get the full Argyle or diced.

4) Some have suggested red hose to pull out the red stripe in the tartan. I would agree -- if there were a red stripe in the tartan! The Baird tartan does have a purple stripe in it, so maybe purple hose would be an option, but if you want to be conservative the navy blue or bottle green would be a safe choice. (I have visions in my head of navy and purple diced hose....)

5) Lastly, many have suggested wearing the kilt pin lower. This is because today, the kilt pin is typically worn very low on the kilt. However, traditionally, the kilt pin has been worn higher. I started wearing mine higher up, about the level you have yours, after noticing photos from the 40s and 50s where men typically wore theirs higher. So where you have yours is very traditional, and I wouldn't worry about moving it at all.