According to https://chernobyl-tour.com/faq_en.html:
staying on its territory for civilians without accompanying guide and itinerary is strictly forbidden
So you should buy a tour with a guide or try smuggling. There are several companies which provide such service – takes you from Kiev to Chernobyl/Pripyat and back, guides talk in English. I have booked on tourkiev.com – it was one day trip with lunch in Chernobyl. You may try 2 days trip if you stay overnight. Radiation shouldn’t be a concern because guide will take through the safe path. There are few zombies but nothing to worry about. Tourists are checked for radiation limit before leaving Chernobyl zone – if they do not carry out too much radioactive particles on their clothes.
There is a lot of questions so let’s start in order:
EDIT
Credit:stackoverflow.com‘