Just to clear up a few things...
A five or 10 point swing is relatively normal following an "inquiry", which is what it's called when someone pulls your credit report. Multiple inquiries for mortgages, auto loans, or student loans within a 30 day period are treated as a single event to prevent people from being punished by shopping rates on the above types of loans.
The amount of new credit can also affect your scores. For some, it can even affect it positively. Don't mistake this for what happens when you have a balance near the high credit limit on a revolving account (credit card, equity line of credit, etc), which hurts scores almost as much as delinquency. The scoring algorithms look at this as a sign of being strapped.
As much info as you may think is out there, the credit agencies do not know your income relative to your debts. Balance on a new installment loan does not generally have a negative effect on scores, unless you have an abnormally high number of installment loans.
Hope that helps.
Edit: Just noticed in one of your posts, that your parents don't have much credit history. That alone often causes inquiries to have a larger impact.