How 'Knightly' can I go?

Having chosen to go down the route of a very bike heavy, mobile army I am now thinking of how to give them a unique identity.  I don't want them to look like White Scars or Ravenwing, and I do want them to look like Knights!  Here are some inspiration ideas (images courtesy of GW)

These are empire knights and bretonnian knights, top and bottom respectively.  Now there are some very obvious unifying themes running through both.  Lances, fluttering banners, shields, and some form of helmet adornment.  They have differences too. The empire unit is very uniform, all the same colours, the same iconography and the plumes on all the helmets.  The bretonnian unit is the opposite, every knight has his own colour scheme, iconography, helmet adornment etc.  They also have a lot more flowing fabric. 

So how does this fit in with my Astral Knights bike army plans?  Obviously I can't have every biker in his own colour scheme with his own iconography etc, it just wouldn't fit in a space marine army.  The fluttering banners I can do, I found this tutorial that might just fit the bill perfectly so I'll have to try it out. I was wondering about giving each bike squad its own knightly order, not a colour scheme as such but just a heraldic image and colour for the left shoulder pad to act as a squad badge?  I think it could look quite cool on the battlefield.  The shields can be modelled on in a small way on most bikers without serious issue and major characters can go all out with elaborate sculpted shield designs. The robes can be done on special characters and are easily available from Dark Angel and Black Templar models. Next I come to the big two issues....

Lances.

I can't find anywhere space marine bikers with lances or even an equivalent weapon so I can't do a wysiwyg job.  So do I kitbash some really cool looking 40k 'power lances' for my special bikers and have to use them as 'counts as' power swords or do I drop the idea or do I invent a new weapon and hope people will play them if I'm up front with the weapon stats and costs?

Helmet adornment.

Do I go for plumes or the icons?  Bearing in mind ease of construction, cost etc I am leaning towards plumes.  I am sure these can be sourced fairly easily and then kitbashed onto normal marine heads.  It would keep things nice and uniform cross the army and also fit with other chapters who have crests etc.  I would worry that animal horns etc would look too chaos, and we wouldn't want that would we?

Any suggestions or comments on these ideas would be really helpful so please feel free to give me your thoughts!