1) Do all ḥurūf put the following ism in the genitive case?
No, for the most part this ability is limited only the ones mentioned in this chapter. There are even some ḥurūf which have no effect on the case of the following word while others, such as prepositions, cause changes to case.
2) Is there any difference between using the prepositions that are ḥurūf verses the prepositions which are asmā’?
In terms of the overall grammatical effect on the following word, there is no difference. There are some technical differences which will be addressed later. Both types of prepositions affect the nouns that come after them by creating the genitive state (jarr).