you can use the handlebars helper and if/else to show certain items
{{#if currentUser}}
<logged in content>
{{else}}
<not logged in content>
{{/if}}
for the user's name, you'll have to use another field for their real name, usually within the profile eg. user.profile.name
assuming the user's name has been set, you should then be able to do something like
{{#if currentUser}}
{{loginButtons}}
{{else}}
{{currentUser.profile.name}}
{{/if}}