UPSC Query????

i need a small advise from seniors who have completed their upsc (civils).... can a CA final student appear for the civil services .???? next year or so

what all i want to know is?

is it difficult to crack the prelims and mains ?

is their any permission to be taken from ICAI?

what is the difficulty level when compared to CA?higher or lower?

how many related subjects do we have during the course? and what are the different subjects?

it would be nice if some one gives me the info.