Lebrun
Proper names like Erin, Kyle, Sam, etc. are not spelled differently in French. The spelling of your name is to remain the same. Counterpoint. If your last name is a color like Brown, Green, etc. you will not use the French words Brun or Verde for them, you would retain your name as is.
dernier, dernière
Translation: le dernier
Same spelling Names of people do not get translated So Obama is the same in American or French - for example
There is a French surname Messon, as well as Masson and Maisson.
last - dernier (masc. sing.), dernière (fem.), derniers (masc. pl.), dernières. French adjectives have to 'agree' for gender and number with the noun.
"I studied French last year."
The name Hebert (Cajun or French) is pronounced "A-bear."
"garder le meilleur pour la fin"
Yes, "French" could potentially be a French last name, as last names can be derived from various factors such as nationality, occupation, or physical traits. It's not uncommon for last names to reflect a person's heritage or ethnicity.
"Je veux parler de mes dernières vacances"
Nothing you mention should have any importance to a relationship between the two of you.