WE need more information--what are the balances and limits on the credit accounts you have open and active?
2/3 of your credit score is based on the manner in which you manage these accounts that are open and active and this is what you should focus upon UNLESS these collections getting paid were recent. (within the last 2 years)
There is no real way to estimate how much your score will change once the collections are deleted because each bureau scores differently.
Yes, if your scores go up it will improve your interest rate.