To answer your 2 questions,
1. I will split the 2 aces. (not very often that we get 2 aces)
2. I'll fight.
What would you do?
1. I was playing with my friend who is very good in blackjack. There was once he stopped me splitting 2 aces when dealer has an ACE. I asked him why. He told me if I do not believe him, just split and let the dealer earn my money. I split both As and I got subsequent 10s for each As. Dealer drew a 10 as well. My split bets were taken by dealer because he has a blackjack while I only had 21 for both As. When splitting As, and a 10 is drawn, it becomes 21 and not considered blackjack. He told me when dealer is on an advantage, I am exposing myself to double danger by bet increment and losing 2. Dealer has more than 30% chance of getting blackjack and after splitting, the max we can get is 21 and not blackjack and splitting As can only draw 1 card each. So there is a high possibility of getting A2, A3, A4, A5, A6. Dealer must draw to 17 and with a ACE counted as 1 or 11, dealer seldom bust with a ACE.
2. When you have a blackjack and dealer has an ACE, take EVEN money or Fight. There are 2 school of thoughts. 1st common school of thoughts is to fight.
Why?
Dealer getting blackjack is 4 out of 13. So 9 chances will ensure the player gets 1.5 payout. Consider we stand and fight, so 9 chances = 9x1.5=13.5units while 4 chances we push with dealer and get 0.
Let's say every unit we bet is $100, 13.5 units will be $1350 divided by 13 chances, if we stay and fight, we can roughly get $104 per blackjack. (average basis) This is what people say in the long run, we will earn extra $4 for every $100 placed. Some blackjacks earn and some blackjacks pushed.
The 2nd school of thoughts agree with the calculation above but in a real life situation, have you ever faced yourself having blackjacks luckily and not getting paid a single cent.
If Dealer has a ACE, player get Blackjack, getting EVEN money is $100 instead of ($150 if player stayed and Dealer did not get blackjack). No one plays 24 hours in a casino 7 days a week. The $4 extra is almost negligible and the saying goes, why be greedy for $4 in long run when the objective is to win during that short session.
Nothing beats having money on hand
The other scenario would be when Dealer has a 10,J,Q or K, and player has a blackjack. There is no way player can take EVEN money and if Dealer draws an ACE, there comes the push.
In a short 2 hour blackjack session, such scenarios happen. Books say fight, but the crunch time would still be having money on hand first. It depends on which school of thoughts 1 would like to be in. For me, nothing is more factual that having a good pair of blackjack keeping the money first than the anguish in watching the blackjack fly away when dealer has blackjack and not getting a single cent out of it.