Problems of a newbie

I have several questions.

Firstly: How can I edit or delete a food item I’ve created myself?

Secondly: I buy my baked goods fresh from the baker’s. When creating a food item (not a meal) without a barcode, how can I enter the baker’s name?

Thirdly: Nutritional tables always show values per 100 g or 100 ml. Why isn’t there an automatic conversion feature in the app that provides the amounts per 1 g or 1 ml for individual calculations? For example, 4 times 1 g instead of 0.04 times 100 g?