YouTube - 300 Workout
for the above? Sub a body part excercise
for example instead of pushups you could do some dumbbell presses
Instead of chinups lat pulldowns
Tailor it to what your gym has
If you can do 200 reps in whatever combo you like without stopping?
You'll feel it... cardio wise
If you get stuck on rep 20 of 25 stop for 5 seconds then keep going
You have to do every last rep
To build cardio try to keep it at 130bpm
and I rotate bike, rowing machine and skipping 5-10 minutes of each.