Instead of making a new post, you can simply use the misnamed and grammatically incorrect Post A Answer box to post follow up questions. This produces a "thread" of questions an answers that better facilitates an ongoing discussion.
Will your users be accessing the database via their web browser?
Are you familiar with Manage | security?
To facilitate the registration process, you can define global fields for the users to use for entering their account information and then scripts set to "run with full access permissions" can use the script steps found in the Account category to create accounts with passwords and appropriate privilege sets.