A majority of D&D characters don’t use feats

Can you use a longbow in melee to get Great Weapon Master and Sharpshooter in a single attack for +20 damage?

It possible for beholder to replace it’s central eye with Vecna eye?

So a darkvision party, who refuse to bring torches or use Light, should still be getting disadvantage in dim light?

Why are all the half-orcs, half-elves, etc always half-human?