It would do you well to actually study the Bible for yourself rather than rely on the testimony of others who know as little as you. Some people call this the blind leading the blind. As to the questions you've raised ...
Biblical slavery was a way of paying off debts. Back then no one declared bankruptcy and actually took responsibility for the mistakes they made. Some slaves were treated so well by their creditors they stayed on even after the debt was paid in full. But at the end of seven years slaves had to set free even if the debt wasn't paid off. Do you see anything unfair here?
Homosexuality is a sin. What people seem to not realize is that any sin can be forgiven just for the asking. Read Matthew 7:7-8 and 1 John 1:9. No one will go to Hell for being a homosexual. That place is reserved for people who consciously want God out of their lives forever. They'll get exactly what the want. Do you see anything unfair here?
Shellfish were forbidden for health reasons. One of the reasons the average Israelite lived to be 70-80 years old (Psalm 90:10) while folks in Egypt barely made it passed 40. While all foods have now been declared "clean", researchers have only recently agreed that shellfish are not the healthiest food you can eat. But God knew this thousands of years ago.
When God separated the waters above from the waters below (Genesis 1:6-8) He was using vaporized water to create a canopy around the planet at the outer edge of our atmosphere to ward off harmful cosmic rays. The rains came when the canopy collapsed. The genealogies in Genesis show average lifespans got progressively shorter after the flood. Abraham lived only 175 years, but Noah who died at age 900 lived to see Abraham’s 50th birthday. Noah’s son Shem out lived Abraham even though he was born 10 generations earlier.
There is no afterlife as such, only a continuation of the present life. We are spirit beings living in physical bodies. The body may die, but the spirit is eternal. So the real question is where you, as a spirit being, will spend eternity. You have a choice between Heaven and Hell. Choose wisely. And no, death is not normal. Man was created to live forever, even in the body. It's sin that brought death into the world.
You don't need scientific evidence to support God. Common sense and a little research will do just fine. In Romans 1 Paul claims that all anyone has to do to see evidence of a Creator is look at the creation. Its perfection, its consistent order render the evolution option totally wanting. And according to Paul this should be sufficient evidence, because God says those who deny it are without excuse. But in my opinion the quickest way to prove God’s existence is to begin studying Bible prophecy.
There are over 135 historically verified, fulfilled prophecies in the first 35 verses of Daniel chapter 11 alone. God called King Cyrus of Persia by name in Isaiah 44:24-45:6 as His agent for freeing the Israelites from Babylon 150 years before the event. Daniel 9:25 prophesied Jesus' entry into Jerusalem on what would be the first Palm Sunday, 483 years to the day after the decree to rebuild Jerusalem was given by King Artaxerxes Longimanus of Persia. The decree was given in 445BC. The prophecy was given in 535BC, 90 years earlier. Alexander the Great refused to invade jerusalem after the Temple High Priest showed him in the book of Isaiah the very dream he recently had that was written hundreds of years before. You just can't make this stuff up.
Or just take a handful of Old Testament prophecies concerning the first coming of Jesus (there are over 300 of them and all were a matter of public record at least 150 years before His birth), and apply any legitimate standard you want: forensic logic, statistical analysis, rules of evidence, you name it.
Even a person of modest intellect will quickly be persuaded. God exists, He is Who He says He is, and He has done all that He claims to have done. No blind faith is required, no rush of emotion, no hocus-pocus; just cold hard logic. In fact it takes a whole lot more blind faith and a stubborn willingness to believe in spite of the facts, to accept evolution as your explanation for the beginning of life.
Prophecy is the way God validates His word. No other so-called holy writings offer this proof. Only God has consistently told His people what He was going to do and then did it to prove Himself to them.
Once you see that His track record for fulfilling prophecy is without error or blemish, you’ll know beyond all shadow of doubt that you can trust Him too. Trust Him to save you from the penalty due you for your sins; trust Him to return like He promised to take you to be with Him forever, and trust Him to guide you through the remainder of your uncertain and undefined life on earth in the meantime.