Making the most of limited transport

I seem to have messed up on buying stuff and have very little transport for the amount of units I have/are on their way.

I have 1 archon, 20 Kabalite Warriors and then 10 Incubi and Drazhar on their way.

I only have 1 venom and 1 raider.

Obviously the quick solution is to get a few more transport vehicles but that isn't financially viable right now.

How would you organise those troops in to transport?

Last thing, I could still cancel my incubi and drazhar order and just get 5 incubi or a combination. I really want those incubi though.

There is always the option to hide 2 squads of 10 kabalites in cover with a dark lance, run 6 incubi and Drazhar in the raider, and the Archon in Venom with undersized 4 incubi. Since Incubi without transports isn't playable IMO, they have the priority.
However, i would strongly advice you to consider transports as your future purchases (no rush, eh, playtest your army as much as you need first). Dark Eldars really need those.

Edit : my bad, you can't have an undersized unit if you have another one. So you could make something like 5 incubi in the venom, and Archon, Drazzhar and 5 incubi in the raider ?

Is it beneficial in anyway to keep the Archon with the kabalite warriors? Or am I better just rushing him in CC with the incubi and drazhar?

With keeping with the kabalites at long range should I keep them there for most of the time to provide cover fire for the CC Units or footslog them in to benefit from rapid fire?

His leadership bubble I find is effectively useless, or very circumstantial.

I'd run him with the incubi (and have done) to get into CC.

For staying at range vs foot slogging to rapid fire depends who you're against. If they want to get to you then kite them, otherwise close in for the rapid fire. Also depends who has the superior ranged and what your opponent is doing on the field.

Would you consider using Papercraft Venoms? When I started DE about 3years ago I printed three of them, one sheet of A4 card each, and I am still using them! Google it, there's a few versions.