I haven't read through the whole thread yet - I've got ds chattering in my ear, but my ds is a nightmare eater - one or two things I was told - the variety doesn't matter too much at this stage as long as it is a balanced diet - i.e. it doesn't matter if he has peas every day, they still count as vegetables.
Do you ever get him to prepare the food? That sometimes helps ds eat more, or if he is allowed to serve himself from a bowl on the table, then he is in control of what he eats. As a guideline, ds has a bowl of rice krispies and raisins for breakfast, a piece of bread , maybe with lemon curd for lunch (and some grapes if I can force them down him) and then something like pasta, peas , cheese for tea.
I do treat ds with ice cream, but only on a Sunday, and only if he's eaten enough of his first course. He is improving - he will now eat spaghetti bolognese, sausages, fish fingers which has stopped me worrying a bit, because he is at least eating some protein.
On Little Angels they suggested letting the child explore the food, without the pressure of eating it - so putting a bowl of fruit out, and just letting them be in charge, with no expectation of eating it, and they might just pop it in their mouths!
It's horrible isn't it - feels very unnatural for a child to be so fussy, ds is improving if that gives you hope - he's nearly 4, and I think he is starting to eat a bit more, but it depends a lot on whether he's growing or not - after a growth spurt when he'll eat relatively loads, he'll eat nothing for a few weeks.
Is he underweight at all? If not, then I would just try and introduce things slowly. Sorry this is so rambling - I'll look back later, when ds is in bed, because I feel like I've tried everything, so I'll try and think of some more things to suggest.