It depends on whether you have been keeping yourself physically
fit all this time, if yes, you can go into "hard" type of martial
arts. If not go for the soft type.
Modern wushu generally have less cultural or spiritual
practices attached, much less than silat. I would believe it should
not be a problem, you may check with you Imam to be sure.
Normally, one training session will be around 2 hrs,
although it may vary, and anyway, stretching and warming up are
indispensable in martial art training, taking up to maybe 15-30
mins. One or two katas is usually expected with self practice and
rest in between.
Anyway, intensity of training progress steadily, you will not be
pushed very hard as it will deter beginners.
This is just a rough guide, as different instructors plan
syllabus differently,