Credit Score Management

i currently have 499 credit score and that’s because i stayed behind on some car and credit card payments. i currently owe 4k total in 2 credit cards and 2k on my car payment. if i was to pay it all off within a week (i have the money) how much will my credit score improve? and after how long can i buy something (either a house or car)? do i have to wait for years, months?

Here’s the background info:
Came to the US in mid-2001, opened my first credit account shortly thereafter.
Everything was going fantastic, making ontime payments, keeping my balance low, until mid-2004 when I hit a bump on the road, which resulted in several late payments on several accounts, a couple as late as 60, 90 days.
Picked myself up a bit, but have been only able to make minimum payments. Cards are maxed out, which is the reason for my score of 580, I guess.
Have about 4K in credit card debt, which I am plotting to pay down completely within the next 3 months.
How much and how quick can I expect my score to increase? When will it reach a respectable level assuming everything goes well from now on?
Thanks in advance.

My credit score was near perfect before this and I was reported just once for a small amount of $13. I am desperate and I have no clue what this will mean to me. Please provide some resources if possible!

I have several negative items on my credit report that will expire after the 7-year limit next year (2002 was a wild one!). I have paid some and others are still on there as collection or charge-off. I have nothing negative since 2002 but I have a lot of student loans in repayment and no active credit cards. How many points can I expect my credit score to rise once the last negative items expire?

Any thought how much it costs to have a credit repair company try and fix your credit report