Hello =) For shopping malls the better quality ones would be Gurney Plaza and Gurney Paragon which are close to where you'd be staying.

Or Prangin mall(Cheaper clothing)/1st Avenue(Quite small.. But has the basic common brands like H&M, Cotton On, Brands Outlet, Padini) /KOMTAR (nothing much here) in the town area.

Queensbay mall is also fine but you'd need to travel a bit and considering that you only have 3D2N, time might be an issue but if it's solely a shopping trip, yeap do go ahead =))

For food.. If you're looking for hawker food you can try Bee Hooi Restaurant close to where you'd be staying. Here is the link:
https://foursquare.com/v/bee-hooi-restauran...37ca59357d7ae92

Definitely less touristy and the fried oyster, wantan mee, char koay teow, loh mee and chicken rice there are yummmy! =)

Another hawker place to go to would be Cecil Street Market Food Court for lunch. Go for the curry mee, duck meat koay teow th'ng and pasembur. These 3 are the must trys! Also less touristy but full of local crowd!

Others which are worth trying would be New Lane Food Court (quite touristy and food is slightly more expensive but taste is still good. Lotsa varieties). For chu char Tek Sen Restaurant is good =) If I'm not mistaken there is a really popular char koay kak stall close to the hotel you'd be staying at. And also apam balik or something.

Do comment if you need more recommendation for food! =) For things to do you can check out Tripadvisor =))