Hi,
you can find in [0] documentation which explain how to configure AEM with Adobe Target.
Regarding your questions:
1) yep, you can use Adobe Target even if you don't have AEM. So if you want to integrate Adobe Target without using OOTB integration, you just only need to insert into your page the at.js which is the javascript used from adobe target.
2) You can complete your poc also in your local environment. The only requirement is to have the Adobe Target and Adobe Launch configured correctly to allow your localhost enviroment
3) No other way, you can do this in localhost and then try to use a test server if you have one environment that you can use for test.
Let me know if you need more info.
[0] Integrating with Adobe Target
Thanks,
Antonio