Puppets and Annexation.

[Soul]

1:Can I annex puppets?(How/why not)
2:Is it better to annex or puppet?(Why/Why not)
3:Is it better to take a sub-state or puppet?(Why/Why not)

General advice about China?

[Lembley42]

No, you can't annex your own puppets (I assume thats what you're asking).
You already control the goverment and so on, so you dont have a justification for it.

Well, if you have the choice, its better to annex because your technology boni applies to their provinces and you can build factories etc. (if its not oversea, then its a bit different, still story for boni though). To annex costs way more infamy, but to puppet is just not that useful - you can just sphere them and you gain the same. Puppets only give you a huge boni to your influence, but you can do the same with investments since the AI is too stupid in general to use it.
What to annex and what to sphere, is more the question. I'd say annex popolous states like Pundjab, but sphere bigger resource-ful nations like Brazil.
To free people is incredibly useful though and at least as an european power your most potent war goal.

Sub-state is China-only. You cant create one, China is just divided into smaller piece because China was just too op before that. It's definetly good to take the sub-states once you westernized. You can never have enough pops! =)

As China, you want obviously to westernize as fast as possible. Note that conquering land grants you technology points, easy targets are Korea and Dai Nam (also Burma & Siam).
Otherwise, you want as with any nation to strengthen your bureacrats first. With China thats remarkably easy (because it seems to be done in a really short time period). Just focus on your top province burecrauts and give them around 80% pay and when there are ~0.6% switch to the next province (I usually quit at 0.6% since the rest will bloom itself pretty quickly and its more efficient to enhance in states there are only a few yet.)
After you're done, try to get as much clergymen as you can, to get better literacy, if needed 4% . You're China, so you shouldnt have any money problems anyway.
Overall its mostly a waiting game. After you're westernized, you will auto win :P
Millions of soldiers, factory workers faster spawning than all 10 factories in a region can upgrade, etc. You only have to make sure that you get enough resources and don't have anything against managing ~6k stacks of soldiers.

You can read up a bit on the wiki :
http://www.victoria2wiki.com/China#China_in_Heart_of_Darkness

[GC13]

Basically, if you want their land for productive reasons then you want to annex. If you just want to keep other people from establishing dominion over them, puppeting them will be much quicker and easier and cost you much less infamy since you can bring a three-state nation into the fold in a single war.

As for why you can't annex your satellite states, it's because this isn't Europa Universalis 4. Before EU4 came out nobody would have thought you could do that.

[Lembley42]

Well to be fair, in EU III you could do the same.

[GC13]

EU4 is what turned it into a sure thing, though, and institutionalized vassalization as something you did as an intermediate step to conquest.