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What does LDRB do here?

Hello.
I've been looking at a piece of code that I'm not entirely sure what it does.

    LDR r0, =str
    MOV r1, #0
loop
    LDRB r2, [r0], #1
    ADD r1, r1, #1
    CMP r2, #0
    BNE loop
    SUB r1, r1, #1
Data Segment Little Endian Format
    str DCB "mCQ5Gtq",0

From my understanding, DCB loads the string into a word of 32 bits, and each character has its own byte. Little Endian Format means the least significant byte is stored in the lower memory address. LDR makes r0 = the string. LDRB loads the least significant byte held in r0, into r2 offset by 1 bit.

1) Does the least significant byte start with m or q? i.e. would it be
<- 0000 0017 (ascii for q) or <- 0000 006D (ascii for m).

2) Does the LDRB operator load the least significant byte from r0 offset by 1 bit, into r2. If so, what would r2 be (just the first loop).

Thank you very much