Can a Halfling use the Hank's Energy Bow? Since He's small, can he use the Longbow?

[Leathros]

Well I need to know that, or I'll have to start all over again lol

[BowStreetRunner]

There are small-sized longbows, although they do 1d6 base damage instead of 1d8. They weigh half as much.

Alternately, a medium-sized longbow in the hands of a small character would be used at a -2 attack penalty.

[Leathros]

Is there any way to shrink the Energy Bow? By spending some GP on it?

[BowStreetRunner]

Is there any way to shrink the Energy Bow? By spending some GP on it?

For +5000gp you can have the Sizing property added to the weapon in question. Magic Item Compendium page 43.

[Chronos]

Magic items can come in any size. Assuming you can get one at all, just get a Small-scale Hank's Energy Bow. No need to spend extra on it at all.