1)Check the buses on TravelYaari or Redbus.Alternatively you can book the Amritsar Shatabdi.
2)Check out the hotel on Trivago/Expedia/MMT/Booking.com/Agoda/Hotels.com/Yatra.
3)Visit Jalianwala bagh,Golden Temple,Wagah Border,Saada Pind
4)Have the famous Amritrari Chhole Kulche or the Amritsari Nan.Also,do have a meal at Bhrawan da Dhaba and Kessr Dhaba. 3-4 days is a lot though.You can cover this in 2 days so a weekend getaway shud be fine.