I love the rainbow analogy Frus. I've only heard it referred to as a spectrum which makes it sound like it's all the same thing, just with varying degrees. The rainbow idea makes it much easier to understand how there can be different labels within the one spectrum.
I've just realised I do most of the things you listed already! I'm forever giving him a list of the order that we're doing things in. He gets cross if we can't do something that I've said we're going to right now but if I explain that we're going to do X,Y,Z first then he'll stop tantruming, think for a moment & then repeat the thing he wants to do with a smile. Most often it's when we're going to visit my parents next so we'll list the days: today is Monday, tomorrow is Tues, then it'll be... and on Friday we're going to Granny's house. "Granny's house! 
" We also write a list of the days & stick it on the wall so he can cross off each day. He cracked us up the other day when we were discussing what we'd have for dinner: "Man-shop?" KFC "Erm, no." "Maybe Friday. " Couldn't argue with that, it was just too cute!
He really doesn't get emotions yet. He's beginning to on an intellectual level I think. Mostly because he likes to comment when Runt is sad... but he'll often say it when he's asleep or perfectly happy! He also likes to make Runt smile. I've been trying to draw his attention to emotions in books & get him to make appropriate facial expressions. He mostly just looks at me, purses his lips & copies whatever sound I make! I think he knows scared though. Sometimes there's a loud noise & he'll say "That's a bit scary" but that could equally be that he used to say "loud noise" all the time & we got in the habit of asking him if it was scary!
I'd not heard of the behaviour iceberg before but I'm aware of the concept. It's really difficult to be able to step back from a situation to analyse what might be going on in his head when he's doing something that's making me cross when I'm so emotionally involved! 
This would be why I really want to do observations on him to analyse once the situation is over & I'm feeling calmer. I feel bad treating him like a research project though. Purely because my dad told me not to, come to think of it. If he hadn't said anything I'd probably be doing obs on a daily basis! What am I thinking?! Why do I let that man get to me?! Grr! This would be the same person who, when I was reassured about being small by being told "All good things come in little packages" he'd smirk & quip "Yes, but so does poison"! I'm going to do whatever it takes to understand my child to the best of my abilities. I can be a mother & observe/analyse his behaviours in a more academic way. I shall do what I want with my child which won't involve comparing him to poison!
I'm not bothered about getting an official diagnosis for a while yet. I don't see that there's a lot of point if I'm going to be home schooling him. I figure the only use to having a label is to help other people understand him or to make sure he gets the support/allowances he needs come exam time. I am aware though that I do treat him as if he does have it. What I can't figure out is whether that's my own issues/training & I'd respond to a completely NT child the same way or if it's that I'm identifying that that's how he needs to be treated! I guess the thing I'm most paranoid about is getting convinced that he does have it & treating him accordingly & ending up with him behaving as if he does when he wouldn't if I hadn't treated him that way! 
I'll stop waffling on now! It helps to talk about my neuroses occasionally! DH gets fed up of it I think!