Looking to pay off debt... or not?

So I'm looking to improve my credit score in hopes of buying a house at some point. My credit score is currently 585 and I have 7 outstanding collections on my report (should be 6 now as I just paid one off). They are as follows:$72, old bill, incurred 7-27-2015, est removal: 6-2018 $341, old credit card incurred 12-13-2012, est removal: 4-2019, settled less than full balance $215, medical, incurred 7-20-2011, est removal: 1-2018 $99, medical, incurred 6-13-2012, est removal: 8-2018 $221, medical, incurred 10-16-2013, est removal: 5-2020 $280, medical, incurred 8-13-2016, est removal: 9-2022 $940, old credit card, incurred 1-25-2012, est removal: 5-2018So several questions here.These "estimated removal dates", some of them are less than 7 years, which I thought was standard for all debts. Does this mean that they will be removed at those dates no matter what, paid or not? Are there some of these debts I shouldn't bother paying?When paying debts, should I negotiate them down? I can afford to pay all of these debts off right now at full price, but I noticed that one of them is noted as "settled for less than full balance". I have to believe that that is obviously better than having the debt still unpaid, but how much better, if any, is it to pay in full?When I pay these debts, how exactly should I go about it? Should I ask for confirmation letters? Should I dispute them initially, no matter what?I guess, in general, what do you think would be my best approach to this situation? Also, this part isnt a huge deal to me but I'm here and typing so I'll ask, if I handled all this tomorrow, what type of boost might my credit see and how quickly? via /r/personalfinance http://ift.tt/2rZXhwA