Sorry, this won't be a full answer as I have to get out of the house but just this leaped out at me:
The last two nights have been quite bad (fed at 11ish and 4/5 but woken up at least an additional 3 or 4 tines) and we're in danger of relying on the dummy too much for these.
If these other 3-4 wakings are between 11 and 4am, I'd just feed at one of them and that will likely get rid of the others. Its perfectly reasonable at this age to be feeding more than twice through the night and to fluctuate in the number of feeds required at night with growth spurts, etc.
Certainly if he's lying there happily, I'd leave him to it, at least he's getting some rest even if he's not asleep and will get used to lying in bed which is not a bad skill for a LO to have (don't leave him there all day, of course - I don't think you would but gotta say that).
At 8.5 weeks, 45min naps can be developmental, so I'd try not to worry about them too much though if you can get a longer nap or two in each day by being out and about, that's probably good. You could try a touch more A time, (say, 5min) and see if that helps but it looks just as likely to me that he's overstimulated (difficult to avoid with a toddler) as under or over tired.