1) In Russian there is commonly to omit the present tense verb ‘есть‘ in constructions like ‘У меня экзамен по математике‘, ‘А у нас новый студент’. This missing verb corresponds to ‘to have’ or ‘to exist’. When you want to ask a question about existence, you might comfortably use this verb as in ‘У вас есть вода?‘ Then if you are not asking whether you have water or not, but whether you have ordinary tap water or mineral, you use construction without ‘есть‘, e.g. ‘У вас вода обычная или минеральная?’ That is, the question with ‘есть‘ asks about existence (‘Do you or do you not have…); without ‘есть‘, the question asks about some feature of the thing possessed.
2) English constructions such as ‘it is interesting to know’ have Russian equivalents ‘интересно‘ as in ‘Просто интересно узнать, откуда он’. If a person who is affected is indicated, the Dative is used as in ‘А мне было трудно’. ‘I am interested in knowing where he's from’, ‘I found it hard/It was hard for me’ are translated not by verbs but by indeclinable adverb-type words usually ending –о (интересно, трудно).