Taken from the Colby Admissions website:
Percent receiving grant aid 36%
Average grant award $30,706
Average financial aid package $31,976
I don't believe applying ED or RD affects the amount of fin. aid offered, rather, you don't have the ability to "shop" for the best offer. I would suggest contacting the fin. aid office directly with any questions, the Colby administration is very accommodating and helpful to prospective students.
In terms of test scores, Colby accepts either the SAT, ACT, or 3 SAT subject tests, and does not discriminate based upon which it receives (
Colby College | Admissions & Financial Aid | Application Instructions).
All that being said, Colby is amazing, and if it's definitely your 1st choice then you should definitely apply ED (regardless of any slight admissions advantage it may give you).
Hope that helps.