File types in Keil's ARM develop tool?

I just start to learn the Cortex M3 using Keil's tool.

My questions are:

1. What are each file types mean? I can not find it in the document.

I have built example code successfully. But there are many file types there (.crf / .axf / .d / .iex / .map / .sct / .lnp etc...)

2. How could I know how many bytes the code needed if it downloadded to the flash?

I am using LPC1768. I would like to see after I modify some code. What it will affect the memory usagea.

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