Hi Again -
Ok, so I think you are right that his naps need to get sorted and then his night sleep will improve. I also suspect there might be a dummy dependence issue. I don't have experience with this and would advise you to check out the props board to get some insight.
The fact that is first feed is small might be because of how long it has been since he last ate. During this time his stomach shrinks so he is not able to put as much in his tummy. I don't know if you have experienced this yourself. If I am absolutely famished I will want to eat loads but I will get really full quite quickly. So the amount I eat is less than I would normally. I don't know if this necessarily means he needs a feed during the night though.
I think he is chronically overtired at this point and so naps and night time sleep are poor. If he seems to want to start the day at 6, then it probably will be better for him if you just go with that for the time being. So when he is awake, feed him, do activity, and then put him down for a nap no later than 2 hours after his wake up. So that means doing your wind down and having him in his cot at the two hour mark. Watch his tired signs and if he is showing tired signs earlier put him down then. But if he is not showing tired signs at two hours put him down anyway. I don't know what kind of baby he is but some babies do not show tired signs or they are very fleeting and easy to miss and they enter into overtiredness quickly. This is especially true with spirited babies. It sounds like you can pretty much set a clock by him to predict when he will wake up, so do wake to sleep accordingly. If he wakes at around 45 minutes, maybe go in and observe him and see what happens at the 45 minute mark. Then once you know what happens, you can do wake to sleep for him for each nap. For example, he may need his dummy popped back in or his legs held down with gentle but firm pressure. Or it could be something else entirely. There are tons of posts about wake to sleep in the naps forum so I would encourage you to browse there. Do wake to sleep for every nap. Like I said in my previous post, it might take a while until you have success but keep at it. Now if he wakes up anyway at 45 minutes and you cannot get him back to sleep, keep activity very low key and short. Then put him back down for another 45 minute nap. So it may look like EASASEASAS for a while and that is OK. The important thing is to work towards getting him used to sleeping through the partial awakening that naturally happens at 40 minutes and to try to avoid him becoming overtired. Some babies are just 45 minute nappers and thankfully most do consolidate their sleeps at around 5-6 months but trying to help him along is a good thing.
For all of his awake times during the day, I would not keep him up past 2 hours. If his naps are short, then do EASASE and go with his flow while still trying to extend his naps.
The third nap of the day (the catnap) is the first that he will eventually drop so you can think of it as a freebie. So if he falls asleep in the pram, go for a walk. Or if he falls asleep in the car, go for a drive (and bring a book or magazines so that you can stop the car and read when he's sleeping

). You can use a prop for this sleep as it is just a catnap. The rest of his sleeps should be in his cot.
His bed time at 7 pm is not too early. In fact, until he is somewhat caught up on his rest, you might want to put him to bed at 6:30. Just see how the day goes and if he is absolutely shattered at the end of the day and it seems silly to keep him up, put him to bed early. I have been known to put Lucy to bed at 6:15 if the day was particularly awful. And this may cause him to sleep later the next morning. Sounds counter-intuitive, but it is true.
OK, now just a few questions: When you introduced the dreamfeed, did his nightwakings get worse? Also, when he has trouble going to sleep either for naps or bed and you say you have to go back to his room, what do you do for him? Just reassure, plug in the dummy, something else? Do you have to stay with him until he is completely asleep? How did you teach him to fall asleep independently? Pat/shush or something else?
It is hard to tell if he needs a feed in the night. That is your call but I don't know if it would be so very unusual for him to need a feed in the night. Hopefully a moderator can chime in on this.
Well, I have really written a novel and must attend to dinner. I hope this helps somewhat. I am by no means at all an expert I just think sometimes it helps to have another person's perspective as it is so hard to think straight when everything is going haywire and you are sleep deprived. Let me know how you're doing and how your night goes. I'll be thinking of you.