I have done pretty much all of those roads in the past (though that experience is mostly exclusive to the bikes) except 2 sections: Emu Heights to Blaxland and St Albans to Bucketty
Sackville Ferry isn't as bad for lowered cars as the main ferry crossing at Wiseman's (where high tide is needed to ensure no scraping). However, it has been 4 or 5 years since I last did the second ferry crossing up at Wisemans (which is the one noted in your route).
On the roads conditions:
- I haven't done the run from North Richmond to Springwood in around 7 years. Involves a few tight hairpins is the main thing that has stuck in my mind
- Unless there is something special at Mt Tomah, I wouldn't bother heading up the Bells Line to turn around there. You only get 4 or 5km of fun roads (plus Bellbird Hill) before turning around - there are plenty more after that point that you would be missing out on
- The run from St Albans to Bucketty last I heard (couple of years ago) was dirt. I wouldn't expect that to have changed unless they have spent a shitload of money sealing it in the last couple of years
- Wiseman's Ferry Rd can be quite bumpy and gnarly in spots. It might be a little better in the car but I doubt it.
- Maraylya-Hillside-Glenorie is your usual back lane 1.5-2 car widths road from memory. Friends have lead me through there on the bike and aside from dodging the more frequented areas, I couldn't see the interest in the road. Again, it might be different in the car
- Sackville Ferry Rd is a bit of fun, not too hard on the car.
- Cattai Rd was resurfaced a few years ago with lovely racetrack hotmix in the fun section. Need I say more on this one?
- The Old Northern Rd is good fun north of the intersection with Cattai Rd, less so south, particularly when traffic is factored in. Condition was good last time I was through there (year or so ago)
- Wiseman's to St Albans last I went through there was mostly 1.5 car widths with short sections of dirt. I have heard since that it is sealed all the way up to St Albans though. No idea of the surface condition though
- George Downs Dr (North through Central Mangrove) is a fairly good road. Plenty of fun north of Bucketty you'd be missing out on though
- Doing Putty Rd and not heading up to Colo Heights is just a travesty, particularly since the run up the hill from Colo River now has a racetrack ... AHEM ... hotmix surface

hmm, must get back there again very soon
Hope that is of some help