First try to get your headlamps cleaned from the inside, if that fails then get new set of headlamps.
You won't need a new battery, halogens are plug and play.You'll easily find the Phillips rally bulbs in car accessory shops(I'm not familiar with lahore), but you won't find the X-Tremes or the Nightbreakers anywhere, you'll have to import them from abroad.
Cultus uses an H4 bulb, such bulbs have two filaments in their glass capsule(one for high beam and one for low beam), so you will need to buy H4 bulbs and thats all.
Its not just lens but the the reflector as well.
If you want to install HID's in your aftermarket halogen projector then you only need to install an HID as normal and use the right bulb like H7,H11 etc.
But, I would strongly advise against that.