She will require 3 rounds of vaccinations before she's 6 months old
You should find out which brand of food it currently eats. If it is not your preferred brand you will still need to buy some. Suddenly changing brands, most of the time, will upset their gut. You can slowly transition: 1/4 new food 1st day, half and half day 2, three quarters new food day 3.
It is recommended that you keep a cat/kitten inside for the first week.
You (or another pet) will need to replace it's littermates and play with it. Safe homemade toys are fine you don't have to buy them. Piece of string, empty thread spool, screwed up piece of paper or peg are all fun toys.
Depending on your vet you can get your kitten spayed or neutered at 1 or 2 kilograms, 2kg is the norm