Does ill-gotten money hinder the answering of the Du`a (supplication) and the means of subsistence?

Sins hinder the answering of the Du`a, and deprive the sinner from means of subsistence; whereas, acts of obedience facilitate making a living. Allah, The Almighty, Says (What means) : "And for those who fear God, He (ever) prepares a way out. And He provides for him from (sources) he never could imagine." [At-Talaq/2-3].

I see horrible dreams although I perform the prescribed prayers, what do you make of that?

All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

Be mindful of Allah while awake and he will safeguard you from whatever evil you see while asleep. We advise you to make the pre-sleep supplications. And Allah The Almighty Knows Best.

Is it permissible for us to sever ties of kinship if our blood-relatives` gatherings/meetings involve acts of sin?

Observing kinship ties is obligatory, and paying your blood-relatives a visit causing their sinful acts to be hindered , then you should do so. However, if their sinful acts continue while you are at their gathering and they didn't respond positively, then observing kinship ties via telephone and the like will suffice in this case. And Allah Knows 

Is Zakah (obligatory charity) due on owned land?

Zakah is due on the land used as an article of merchandise and was originally bought for that end. Zakah is due on it at the end of every lunar year. Its value is estimated, and (2.5%) of the total value of all such lands owned by the questioner is given as Zakah. However, no Zakah is due on the land used for building a house, or an agricultural purpose.