Your link worked and I read this whole thread. You're doing good so far and those four leaves will likely just be two. They can look a little funny when they first emerge.
Don't trust that meter for pH. I've had one for years. Handy for checking for moisture further down so you don't overwater. That little plant probably has a tap root 4x as long as it is tall if not longer so don't worry if the top inch or so of the soil is dry. That leads to overwatering and root rot keeping it wet to the top. Get used to the weight of the pot and let it get pretty light before you water it unless you see some drooping in the plant first. After it gets a bit bigger keep track of how long it goes between waterings.
With an auto you want it in it's biggest pot from the start to get the most size out of them. I've been growing them for a while but more for breeding purposes than yields and they stay small in small pots for sure.
The light meter on that probe doesn't tell you much but is useful for finding areas that can use a bit more light by comparing light levels. A foot under my 1000W HPS it's right off the scale over 2000 then I checked under my 8 fluoro tubes and it barely hit 200 a foot away so I yanked that out and put a 400MH over the vegging plants. They're getting too tall so as soon as I can crop a couple plants in a week or so I'll repot them and move them in for flowering.
You seem to be off to a good start. You get an exhaust fan yet? A 4" inline fan should pull enough if it has a fairly good cfm rate. Figure about 1/2 the rated cfm with a filter attached. If you used a 6" carbon filter with the 4" fan you would get better air flow and the filter will last twice as long. Even one plant can stink up the whole house and yard depending on strain.