Yes, I work on SAS programs every day. I have been programming in SAS for a long, long, long (almost 10 years for every 'long') time, in a variety of industries. Currently, I am an instructor and course developer for SAS.
As for interview questions, I can only point you to previous forum postings and the various user-group papers on selecting programmers for a job working with SAS.
Since I was a former Literature major, I am very fond of T. H. White's book about Merlin and King Arthur in which Merlin teaches Arthur over and over again that:
"education is experience and the essence of education is self-reliance." Reading about interview questions and being academically prepared for interview questions is different from having experience with the things that are being asked about.
Taking classes, writing programs for your own learning, experimenting with SAS code -- getting real experience with SAS code is the best preparation that I can recommend prior to either interviewing for a job or taking the certification exam.
The best way to prepare for BASE SAS certification exam is by reading ( and re-reading) and understanding the books 'Little SAS Book' and Base SAS preparation guide. Try to program the problems that are given in the books. I am pretty sure, if you are a novice SAS programmer, your log will be full of error messages and warning. That is perfectly fine. SAS is a programming language and you need to learn it by 'doing'. I am a junior SAS programmer and this is the way I learned. The more effort you put in, the more you will be rewarded.
thanks for the info......currently i'm taking base sas certification course..from sas authorized training centre.they are giving the material required for sas .but i wanted to know if any books other than this would help.i also wanted to know how to prepare for the certification exam.