Can I ask people who have innovations, even if the innovation constitutes an act of disbelief about all matters of the religion? For example, can I ask them if an act is forbidden or something regarding Waswaas (obsessive doubts)? There are not so many Salafi shaykhs in my city, I think.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger. 

We noticed from your questions that you suffer from Waswaas (obsessive whispers). The best remedy for Waswaas is to ignore it and completely repel it. We also noticed that you exaggerate in accusing people of disbelief and innovation, so beware of this serious pitfall. You should know that the scholars held different views regarding seeking the fatwa of the Faasiq (dissolute/impious) Muslim who practices innovations or other sins. The best statement in this regard is that of Ibn Al-Qayyim as he wrote about the permissibility of seeking the fatwa of the Faasiq in case of a necessity or dire need. He said:

“If a Faasiq scholar issued a fatwa for another Muslim, it is rejected, and this Muslim should not have sought his fatwa in the first place. The Faasiq may follow his own fatwas and he is not obliged to issue fatwas for others. As for the scholar whose righteousness cannot be affirmed or negated, scholars held two different views regarding seeking his fatwas. The correct view is that it is allowable to follow his fatwa and it is allowable for him to issue Fatwas. I believe that the same ruling applies to the Faasiq unless he is openly Faasiq and calls people to his innovation. The ruling on seeking his fatwa is the same as the ruling on praying behind him and accepting his testimony; it differs according to the place, time, ability, and disability. The religious obligation is one thing, and its actual application in the real world is something else; the one who is versed in the religious law is the one who applies the religious obligations in the real world and observes them to the best of his ability, and not the one who creates hostility between the obligations and reality. Every age has a different ruling, and people differ according to time; people tend to mirror their own times. When impiety prevails in any given time or place, if the Shariah forbids the Faasiq person from leading the prayer and rejects his testimony, fatwas, and political leadership, then the Islamic rulings would be put to a halt, people's affairs would be ruined, and most of people's rights would be lost. In such a situation, the more righteous should be given precedence over the less righteous when there is the ability and choice to do so. As for times of necessity and prevalence of falsehood, there is no choice but to adhere to patience and observe the least acceptable manner of forbidding evils.” [I‘laam Al-Muwaqqi‘een]

This great statement properly addresses your question, assuming that it is real and not based on mere Waswaas.

Allah knows best.