Ramblings on writing, reading, spelling, etc. and something cute Katie wrote

I know they are all different and there is no sense in comparing, but it is hard not to. My oldest daughter hardly ever writes anything independently. She is just beginning to do so now, and I sense that she will be a good speller, because she already has a good eye for when something doesn't look right because it's not spelled right, though we haven't yet done any formal spelling. I do wonder, however, if she doesn't write as much because she doesn't want to write unless it is spelled correctly. Her fine motor skills have always been on the later side of normal, and she is left-handed, FWIW.
On the other hand, my second daughter Katie is six. She's had really good fine motor skills and the ability to write things fairly small from an early age (last year she wrote almost the entire alphabet in one line on the back of a business card). LOL! She's also more likely to just write stuff for fun without a care in the world for how it's spelled. I've read some things about spelling that mentions just taking words they spell wrong in their writing and adding it to their spelling lists. I could definitely see being able to do that with Katie.
My oldest daughter, well, she seldom mis-spells anything, because she seldom writes, so that would be hard to do.
I just wondered if it is normal for a six-year-old to be writing (for fun) what amounts to whole paragraphs, while my eight-year-old is just beginning to write sentences and lists on her own? Now, I do see definite growth and improvement in Elizabeth, so I'm not really worried about it, just surprised at the differences in them. Elizabeth is very visual and kinesthetic (can't sit still long, but getting better at that). She reads well and does what she has to do to get by in math. On the other hand, Katie loves workbooks and loves writing and math (and seems more auditory, so far), but just seems to do what she has to get by in reading. It's really interesting to see the different learning styles. We did Pathway Readers with Elizabeth but quickly stopped doing the workbook part with her because her reading ability was ahead of her writing ability. However, I can definitely see Katie being able to do (and in fact, loving) the workbooks. LOL! That's what we have on the agenda for her this year, so we'll see.
I just found this on the floor in the hall, in Katie's journal (that we started but have never written in before now).

I Laic Playing
But i no i am my
FRenDS Forevr
FRenDS LUV
RUNiNg But
I Laic Playing
in th PRc But
I no i wiL Love
my naBrs
and my FRENDS
Forevr and evr

So sweet! (I did insert the proper spacings to make it easier to read.)
I don't want to do anything to disrupt this natural love of writing, but how do I casually bring up the proper spelling of those words without pointing them out here? I don't want to do that, because I don't want to make her afraid to write what she wants for fear of having it nitpicked to death, KWIM? However, I do want her to learn the proper ways of spelling them soon, if she wants to use them in her writing, because I don't want her to get used to seeing them with the wrong spelling (something Charlotte Mason wrote was about not letting their eyes rest too long upon the wrong spelling or they will begin to think that is the right way, or something like that; Jeannie Fulbright mentions it on her site).
http://www.jeanniefulbright.com/cmspelling.html
She's finished Reading Made Easy and is up to about book 3 of Explode the Code, FWIW. She hasn't read enough yet to really become used to the right way to spell these common words.