They will ask you to return your postpaid simcard, and give you the option whether u want to pay the outstanding (unbilled) amount with your RM100 deposit  /or/ wait for the next bill then pay , and rebate of RM100 back to you.

I suggest you offset your unbilled amount with your RM100 deposit and make your last month's bill slightly more than RM100 because i am 95% sure they wont return the few ringgit leftover deposit to you.

To answer your question, the hotlink card will be given to you on the spot,and you need to pay RM35 . THe hotlink simcard comes with RM10 preloaded credit and 30 days validity. It will take around 2 hours for the hotlink to be activated and a few days for it to be fully registered in hotlink system. So, GPRS/MMS can only be activated 48 hours later (for my case).

good luck. If they ask you , just tell them u are going oversea.