Hi,
I will try to reply to all your questions about our product.

before a small introduction: Easy Profile extends Joomla user management (not replace), so pages like registration and edit profile are the same of Joomla with many improvements (like tabs). With this way all Joomla user plugins will works, for example I see from your screenshot that you use a plugin called "User - Profile" (installed and disabled by default in all Joomla installations).

a. I currently use the Joomla login module. Would easyprofile replace the Joomla login completely?

No, you can use Joomla login module or some other login module provided by thirty party developer (you can check this with our Free version)

b. Would easyprofile import my existing user database?

Easy Profile have a import feature, but basically all pre-existing users will be available also in Easy Profile, you do not need to import these users. (you can check this with our Free version)

c. Can certain fields be "locked" so users can't change the info? For example, I have the name, userid, and email address fields set so users cant change any of that information. I had to find someone with enough knowledge to make changes to the php code to make that happen. Will easyprofile lock those fields, or will I have to find a smart person to make a change to the code?

Yes, you can set readonly mode for some fields, keep in mind that userid is not possible to change (this is not allowed by Joomla), and for username you can already use Joomla options to not allow to change it. (you can check this with our Free version)

d. The features list lists several items I don't understand. I web search didn't help me understand them. I was further confused since the lists don't seem to have any frame of reference. For example, the first feature under the paid subscription reads "All Types (except Google Maps) - all types of what? What does easyprofile do with that "type". I'm confused about several other features as well:

You can create custom fields with differents types, see screenshot "custom fields types".

1 what is the difference between "search users", "search module" and "Joomla Search Plugin"?

Joomla have 4 types of extensions: components, modules, plugins, templates. So:
- search users: you can create User Lists (from menu manager), when you create a user list menu item you are able to add also search form
- search module: we provide also a search module, maybe you want to add search form in module position instead in a component page. or you want to add a search form in another component page, see screenshot there is a article pages with some modules
- Joomla Search Plugin: Joomla have a own search feature and module to search article, categories, contact, banner,... with this plugin is possible also to add user search by name. Basically a Joomla search module will be able also to return users results.

2 Is there a difference between the "Users List Module" and Joomla's User Management

In screenshot you will see also user list module, you can add a list of users in some module position.

3 What is a "Content Plugin"? An "Author Plugin"?

- Author Plugins: read docs at http://docs.easy-profile.com/index.php/article/author-plugin, It allow you to add avatar and link to profile page in articles
- Content Plugin: read docs at http://docs.easy-profile.com/index.php/article/content-plugin, it allow you to add user infomation in articles, custom module and in all parts where are supported Joomla content plugins
see also at https://www.easy-profile.com/home/addons-integrations.html the description about these plugins

4 What does "Add/Remove Usergroups Conditions" mean. Will it work with existing Joomla information?

You can add/remove users from usergroup with conditions based on fields value. It not works with existing Joomla information, you can add conditions only on Joomla core fields and Easy Profile fields, but the effect of usergroup condition will be loaded after saving a profile. Usergroup conditions are disabled in Free version, but with Free version you can understand how it works

5 Since I haven't ever used easyprofile, I don't know what "Images and Avatar fields improvements(Crop & Webcam, Path to store)" means. I can't determine what's improved since the last version. Can you expand information about it's current capabilities?

You can choose between 3 ways to upload avatar, basic (you can try this in free version), Crop & Webcam or Drag & Drop (like this site).

I recommend you to try Easy Profile to understand how it works.