Regarding Yorktown's situation, have read that by 06.30 they have launched a CAP of 6 F4F and were recovering the 10 scout SBDs, and immediately after that they started respotting for strike (17 SBD, 12 TBD). So in theory they could have launched not long after TF16 started their launch (depending how long it took to respot) However, the staff considered the IJN position to be well out of range for TBDs and F4Fs at 200 miles, so in OTL Fletcher waited until they got in range. Also in OTL, Yorktown's radio team initially failed to pick Amari's contact reports, whether in this ATL they will miss Chikuma 1's contact report too is matter of speculation, so their reaction might be delayed until positive radar and visual contact with that scout.
If Yorktown is going to launch anything after they realized they were spotted, probably it will be just the VB-5 SBDs alone, but possibly both VS-5 and VB-5, keeping VT-3 and all the fighters still on board. But for the purpose of this ATL (a japanese victory), like i said earlier one can perhaps have Fletcher risk waiting until it's too late.
As to the TF16 launch, indeed their formation would likely be even more disjointed if they realize they have been spotted even before starting their launch, probably the SBDs will depart immediately without waiting the TBDs, all this radically affecting the sequence of US attacks and even whether VS/VB-6, VT-6 and VT-8 will find Kido Butai in the first place. So let's say only Kaga is hit and set aflame by SBDs.
As to the japanese attacks, perhaps it's an unlikely scenario but as Nagumo knew that Midway inbound strikes are on their way towards KB, as soon as he has the TF17 contact report (just one carrier), he might opt for a quick launch of half his strike force which could be quickly spotted and take off before 07.00, namely 9 each D3A from Hiryu and Soryu, 9 B5N from Akagi and say 15 from Kaga with perhaps 9 Zeros. 18 D3A and 24 B5N would be enough to kill Yorktown. As he deals with the Midway strikes, and continues to receive more contact reports of TF16, he could launch the balance of 16 D3A and 19 B5N with another 6 or 9 A6Ms between 08.30 and 09.00 before recovering Tomonaga's men. This strike could kill one of TF16 carriers (say Hornet). So two down, one to go. But they are piecemeal attacks and likely to suffer prohibitive losses against the swarms of F4Fs on CAP. However, once any potential US attacks have been weathered out, surviving KB carriers (let us say Akagi, Hiryu and Soryu) would then launch Tomonaga's men around 11.00-11.30, namely 17 D3A from Akagi and 18 B5N from Hiryu and Soryu plus some Zeros to kill Enterprise.
If Yorktown is going to launch anything after they realized they were spotted, probably it will be just the VB-5 SBDs alone, but possibly both VS-5 and VB-5, keeping VT-3 and all the fighters still on board. But for the purpose of this ATL (a japanese victory), like i said earlier one can perhaps have Fletcher risk waiting until it's too late.
As to the TF16 launch, indeed their formation would likely be even more disjointed if they realize they have been spotted even before starting their launch, probably the SBDs will depart immediately without waiting the TBDs, all this radically affecting the sequence of US attacks and even whether VS/VB-6, VT-6 and VT-8 will find Kido Butai in the first place. So let's say only Kaga is hit and set aflame by SBDs.
As to the japanese attacks, perhaps it's an unlikely scenario but as Nagumo knew that Midway inbound strikes are on their way towards KB, as soon as he has the TF17 contact report (just one carrier), he might opt for a quick launch of half his strike force which could be quickly spotted and take off before 07.00, namely 9 each D3A from Hiryu and Soryu, 9 B5N from Akagi and say 15 from Kaga with perhaps 9 Zeros. 18 D3A and 24 B5N would be enough to kill Yorktown. As he deals with the Midway strikes, and continues to receive more contact reports of TF16, he could launch the balance of 16 D3A and 19 B5N with another 6 or 9 A6Ms between 08.30 and 09.00 before recovering Tomonaga's men. This strike could kill one of TF16 carriers (say Hornet). So two down, one to go. But they are piecemeal attacks and likely to suffer prohibitive losses against the swarms of F4Fs on CAP. However, once any potential US attacks have been weathered out, surviving KB carriers (let us say Akagi, Hiryu and Soryu) would then launch Tomonaga's men around 11.00-11.30, namely 17 D3A from Akagi and 18 B5N from Hiryu and Soryu plus some Zeros to kill Enterprise.