Hi grandmx4! I have a small
Crepe Myrtle (Lagerstroemia 'Ebony Flame') Also known as 'Best Red' growing in a container and I never trimmed any branches or leaves when I planted it last August/September. I can't offer advice on fertilizing because I'm really bad about feeding my plants.
Hopefully someone else who grows this beauty will pop in with suggestions regarding the fertilizer.