I've noticed that Experian has more negative remarks for me on their report than do the other 2 credit agencies. Should I concentrate on removing the remarks that are consistent through all three bureaus first? Which agency is taken into the most consideration when a creditor is contemplating extending credit? How is a FICO score calculated and what role will each agency play in the evaluation?
I think the FICO is largely ignored by most creditors. It's a good starting point, but they're going to run their own models relevant to their needs. For example, an car loan company is going to care more about your past car finances than the fact that you had a late payment on your credit card six months ago. It's still important, but the only people who determine your worthiness solely on FICO are companies determining who to mail-bomb with credit card offers this week. Likewise, each creditor has their own preferences for which bureaus they check. Some creditors don't even pull the reports themselves -- they pay a third party to pull your credit and run you through THEIR models. When I review my credit reports, I hit all three bureaus equally. No sense hammering away on just Experian when my next lender prefers Equifax.
You have 3 FICO scores- one that's based on each of your credit reports from the 3 major CRAs. The vast majority of mortgage lenders will look at all 3 of your FICO scores. Most auto lenders will these days too, although they often have other scores they consider that are supposed to evaluate your risk specific to financing a vehicle. I would focus on the negatives that are found on all 3 first and then go on from there. If you're getting ready to apply for credit with a certain lender, you can always ask what credit scores they will pull. If you have a competent person on the other line, they should know.