First, pull all of your reports from annualcreditreport.com - choose the "printable" option and pdf and / or print your reports. Those will have the most complete information. Then go to optoutprescreen.com and opt out, which will make it less likely for there to be new surprises on your reports. Look up the SoL (statute of limitations) for your state. For the medical items, try to figure out if there was an insurance or billing issue - that might save you some cash. Also, sometimes you can qualify for financial aid with the hospital. Then check out the HIPAA process (you'll have to google it) and determine what you want to do before you consider contacting the CA.
Ideally, you're going to want to deal with the OC instead of the CA - feel free to call them and see if they can / will recall the CA and delete reporting in exchange for payment. Also, I'd recommend sending a DV letter ("I request validation of this debt") ONLY to items that you can either pay in full or that are beyond statute of limitation. And...do searches here for the CA and OC names to see what others' experiences were with them. Posting individual items and asking advice on each one, removing personal info, is a good way to get specific advice on each item. (I would not post all of them in the same post. I, for one, skim those and usually don't respond because it's really overwhelming).
Starting Score: EQ 583 TU04 619 EX 592 (lender pull) 2010
Yes, after the 30 days, they are not required to respond. However, DV letters frequently result in a variety of outcomes - one of which is they're ignored, but the others are that a CA could delete because they can't validate, one of which being it inspires a response with an accounting of the debt, one of which is that they send a settlement offer...if you can pay in full, it's not really a terrible idea to DV before sending a PFD. (And I've had PFDs ignored more than DVs, in my personal experience)