In the PHB description of the Flaming Sphere reads, "...any creature that ends its turn within 5 feet of the sphere must..." Does this mean flaming sphere effects a sphere with the diameter of 15 feet (5 feet from itself, 10 feet towards either direction)? Also does ramming the sphere requires placing the sphere at the location of the enemy directly or will it still damage as long as the creature is in the effected range of the spell.
The flaming sphere is only 5 feet wide. So on a grid with 5 foot squares it would effect a 3x3 area with the sphere in the middle. For ramming, the spell specifically says:
If you ram the sphere into a creature, that creature must make the saving throw against the sphere’s damage, and the sphere stops moving this turn.
This means you use your command of the sphere to move it directly into a creatures space (thereby hitting it) and they have to make a normal Dex save, and if the sphere hits the target before moving its full 30 feet you lose the rest of the move distance.