Any plans to implement an SKU search for the customer(if so, when?), or should I just plan to use the custom1 field.
No immediate plans to add a search for the SKU on the application ("server") API but we'll add it to the to-do list.
You're probably already aware that you can search for products by SKU in the Admin API?
So, for the customer... you will probably need to use the custom1 field for now, as you say
--Brian