I am going to weigh in on this from my experience in the past few months. I have been charting my score watch alerts and seeing what makes the most changes in my score. So, this is just my experience and other's may have different experiences.
Anything that is a charge off/collection such as a credit card increases the score more than having a collection removed.
The newer the reporting such as a 30-day, 60-day or charge off, the more the increase in your FICO score. So, I would start with those things that went bad in 2007, the move backwards as the older it seems the less it is hurting your score. (30-day late in July, 2007 was removed and my score alert for that day went up 29 points).
The collection account for me and my DH that was reported in the past 1-12 months that were removed gained anywhere from 5-12 points, most 5 points, though.
Also, had 1 credit card, and 30% of your score is based on revolving credit and how the utility and management, open discover card with 1100 balance, reduced the utility and saw a 24 point gain.
I don't know a lot about mortgages but I am closing on my home in the next week with our local bank and they consider several things in approving their loans such as your score, your overall report and what it looks like, your debt to ratio income, etc. They did tell me that collections accounts such as medical was not really considered in their determination; however, if you go through a mortgage account they do consider them from what I am told.
Keep all letters/documentation from any creditor that you get that says they will remove it, as sometimes it takes the CA up to 90 days to make the correction, so that when you get ready to apply for the mortgage and you go through the bank, you can provide that to them as proof that it is in the process of being removed.
Me and DH have scores in the mid 600s and there were a few things that were negative on his report that I had documentation was being removed from the company, so this help us, as we would have had a higher score if they had already been removed.
Good luck!