Manchu will declare war on you within the first 50 years probably twice and will drag Ming along with them even if Oirat Horde is your overlord. If you are free this will be more often since in both playthroughs I had they just love to declare for Xilin Gol.
Really curious how you will play that out as I was never able to in my first playthrough. If Oirat Horde is weak their ally Tibet is not, when you declare Independence Manchu usually declares conquest war immediately (maybe during a five year truce immediately after a war?). So at least 3 large stacks probably more with only 5 cities. Not a lot of room to maneuver.
If you are planning to conquer West remember you are Buddhist and a Horde. The overextension and Religious rebellion penalties are really bad for a Horde, I really don't think you will have as much manpower as you think. Looking forward to your attempt, will definitely follow to see your strats.
Manchu DOWing me is so predictable I swear it's hard coded. What sucks is sometimes the oriats will DOW Uzbek or chatagi before Manchu attacks. That would be a restart. I definitely don 't want to fight Manchu and the oriats at the same time. I've tried a few times, and been annexed the same number of times.
If Manchu DOW oriats when at peace however...
Manpower will indeed be a issue. Ming will not. They will love me, ally me and then never do anything when I call them to arms or I will destroy them.
Buddhist is not the best religion in EU4. I'm sure some of my most zealous subjects will convince me to embrace Islam.
I will take exploration and see how that works out.
Hopefully it doesn't take 20 restarts like my Byzantium game lol. I am rather OCD. I won't proceed with the game proper until my strategy is perfect....which will hopefully happen sometime this weekend.