For me dong God’s will is actually the most important thing in life. It’s not easy and I can’t say I dont battle against my own will and things of the world or other. Happiness is not the most important thing, in fact it doesnt really matter much, but I find the less it matter the more it is given anyway. God is that good and that loving that even if it’s not something we really strive for He gives it anyway. I don’t consider going to Heaven the most important thing, because if I do God’s will to the best of my ability then I trust in God’s mercy and know He will take care of me and will keep me with Him.
As for possessions, I dont believe we are all called to give up everything and follow him, some may well be and that will be tricky possibly and that is likely why He in His infinite wisdom would ask such a thing. Most of us should be prepared to use all our possessions for His glory remembering of course that they are only borrowed and not ours as such but His which He has kindly given us for this life to use for His purpose. While we remember that, it is easier to share what we have for all. So we should use all ‘our’ possessions including our talents and abilities for His greater glory. We should exercise modesty in material possessions and share with those who have less than us.
Your other questions are more complex as it is you who need convincing of those answers, perhaps? not always those people you mention. though perhaps you ask as you may fit in those category’s. Apologies if I offend I do not mean to. Remember only that God is closest to the suffering which is in some way all of those people you mention and all they need is to trust in Him. He knows what is best for them and would not have allowed them to be in those situations if it were not best for them and the Universal church. Do not be tempted to think in terms of life ending with this physical life, life does not end here…so this suffering which we endure here is but a blink in time. God does not abandon these people, they may abandon Him, but He is with them. There physical body may endure suffering but their souls can and often do move ever closer to Him. Don’t assume the suffering are lost or are useless just because society looks on them as such, they are redeeming the so called ‘successful’ of our culture. We should be thanking them for their sacrifice.