Superman is weak against kryptonite.
Yes, a red sun.
Superman has two main weaknesses: Kryptonite, and magic.
The same as Superman - kryptonite.
Aside from the usual human frailties, Lex Luthor's primary weaknesses have been his pride and arrogance. Occasionally, his extreme jealousy of Superman has also led to his defeat.
Superman, Batman doesn't have any powers
Would totally depend on the circumstances. Batman knows a great deal about Superman's weaknesses and could thus gain the upper-hand by exposing him to kryptonite or a red sun. The batman from the "Red son" storyline (Where superman was a communist) Batman was able to beat him using those weaknesses. However if Superman decides to fight batman without batman being able to prepare, superman would have won in about 1 picoseconds.
No.
Wonder Woman is more powerful because she has no weaknesses, both physical and mental. Superman can be killed/harmed by Magic, Kryptonite, red sun rays, and Omega Beams.
His weakness is famously kryptonite, and his strengths include super strength, super ,speed, super durability, and super senses.
In terms of raw physical strength, Superman is typically considered to be stronger than Hancock. Superman's powers are shown to be nearly limitless, while Hancock's abilities are more limited and come with weaknesses such as vulnerability to certain materials.
Superman beat Goku. After going through all the stats, It's clear why. Goku draws his Ki from a finite pool of energy. In time, that pool of energy will run out. Superman can increase his power by absorbing radiation from the sun, or any yellow or blue star in the universe. Even if Goku knew about Superman's weaknesses, he wouldn't use them against him. Goku's all about a fair fight and seeing his opponent give it his all, even if it costs him the fight in the end, which it did.
Okeanus was a primordial god and the personification of the ocean on which the world sat. He was not a super hero. The gods didn't have "weaknesses" like superman. They were essentially omnipotent and could do whatever they wanted within their realm of influence, and even beyond.