David, you might want to check this topic: http://www.oxwall.org/forum/topic/6911

Answering your questions, profile questions that have string of characters are custom questions ( those each admin user adds according to his needs).  They are encoded to avoid questions with the same names.

Some questions have regular names, for example "password". Those are questions that come within the Oxwall standard package.

Unfortunately, we don't have a diagram showing how tables are connected.

Can I change them? to something reasonable

What you are trying to achieve my changing the internal profile question names? These are never shown in the site.

Bc i need to manually add people to the site, and I can do it easier through the backend, if it made sense.  Even timestamps and dates look strange.

Unless there is a plugin that allows me to manually add people

David, the best way is to add users manually from the front end. Simply by clicking "Join" button. If you will be adding users manually into the database you will face a lot if issues. One of the important ones is password generation. Just using MD5 hash won't work.

You can add users manually or use "Contact Importer" plugin to invite your friends to join your community.