Germany vs the following civs... I answered the questions assuming you are using RE patch.
Japan (Been trying Double-Rax Xbow/Pike spam, Semi-FF, and Merc FF) hard MU, if you xbow rush ashi/yumi+clubs will beat you, if you FF japan will get a hell of a big eco :(
Probably best to xbow/pike rush and constantly harass shrines with pikes.
India (Been trying X-Bow Defense) Again pretty hard MU, staying defensive with xbow/pike sounds good though.
China (Been trying 20 Xbow Semi-FF) Go xbow start and get uhlans ASAP make sure to get 5 pikes first batch otherwise you'll get **** by 7 steppe rider shipment.
Iro (Usually do X-Bow defense..) Another OP civ so difficult MU. Again xbow/pike defense is probably best option.
Sioux (Usually X-Bows/Pike colonial, and Semi-FF) Sounds fine IMO, if you get fortress ship BR ASAP they completely own sioux units
Aztec (Not even sure where to start here..Haven't played vs Aztec in forever) Uhlan start with 8 xbow shipment may be good IMO, take out the SK with xbows and let your uhlans then take down the mace shipment. Play defensively though. Get rax up ASAP since you'll need xbows/pikes as well.
What strats can I expect to see out of these civs and what strats should I try to use to counter them?
Most of the civs you listed seem to have kinda lame rushes (japan has lame units) so pretty hard MUs. IMO germany will beat sioux though and have small advantage vs china.
Also.. Ottoman Fast Revolt.. Best way to counter is to rush them?
Yes. Don't let him fast revolt, because if he does you're probably going to lose since it is difficult beating imperial hussars when you're in fortress (dopples will counter, but CM beat dopples quite easily :( )