What would it cost to change your ticket to LAX-ORD-DEL on AA? That's what I'd do, for the most AA miles... The Elite Qualifying Miles, plus if you have status, the elite status Bonus (Redeemable) miles as well (BA does not give elite status bonus miles.)

1) Get all the miles at 150% bonus into BA and keep them there for future travel on AA? (43,251 BA miles; not quite enough for an international flight)

I'd earn AA miles all the way. See my first paragraph.

2) Do 50/50 split with BA (LAX-Lon) American (Lon-Del) = 24484 BA miles; 15635 AA miles. Is this even possible since BA wont give me credit on the transatlatic portion? Then buy 516 BA points and use 25K later for a domestic flight here in the US on American/Oneworld sometime in the future?

Yes, you can do a split. BA miles can be useful for upgrading, or flying partner airlines. But if you do not plan to fly BA, why go to the bother?

3) Do a 50/50 split with any 2 of the BA partners (ie - Alaska & American). Funny enough, the Alaska website does not state any transatlantic restrictions. This will give me 20,408 Alaska Miles and 15635 AA miles. I dont have an Alaska account, but I suppose I could open one.

Yes, you could do that.

4) Have the miles go somewhere else that I am not aware of yet? Possible to have them go to a Starwood Acct and bypass the Airlline Partners alltogheher.

You'd have to check the airlines' or hotels FFP for terms and conditions.

5) Any chance I can covert/transfer Alaska miles to AA?

You can see what the "cost" would be on www.webflyer.com's Mileage Converter; miles can not be transferred between AA and AS.