Some of your choices seem mutually exclusive.
1) DPM allows the credit card info to be entered through a URL at your site.
2) DPM is for one-time charges, though you can probably set up a subscription from a previous DPM transaction inside the control panel. If you want to do automatic recurring billing, you should look into CIM, hosted CIM, or ARB - probably hosted CIM with an iframe popup given your other requirements.
3) Not sure what you're saying here. You will need to be PCI compliant to some extent regardless of API - even solutions that go through Authorize.net will require basic password security on your end. Using DPM does allow you to avoid messing with data security, however, since the credit card data never actually passes through your hosting.
4) You don't technically need SSL if you're using DPM. However, nobody will enter their credit card info on your site if you don't have it. SSL certificates only cost like $50-$60 per year, just buy one.
5) None of the API's involve you storing credit card data. AIM, regular CIM, and ARB do involve you transferring credit card data through your hosting, however.
6) Every API returns a transaction ID, and generates an email receipt to the customer unless you turn that off. You should also receive settlement reports yourself and reports on failed transactions and so on.