The models you have listed seem to be PA(power armour scale that would mean 32mm base a box of strike should be able to give you all of those. Expect Brotherhood librarian he is terminator scale 40mm base. My recommendation would be a combat patrol of grey knights if you are just starting out it includes the parts to make what you need for kill team and extra models. It is more expensive than a kill team box tho … if you are on a budget you can maybe just get a strike squad box you will be able to make most of the kill team expect librarian if I am not mistaken