Do read the thread referred here.
But to sum up -
Taxes for flights within US is $5.60 per segment.
Assume you also know that Avios cost is per each segment based on the distance band, and NOT the total of full distance traveled. Therefore if you need to connect somewhere, then your cost would be the cost of 2 segments (individual cost per its band) added together.
You can only book 11 months out from departure as that is the limit of AS reservation system.
Go to AS website to check the saver availability before calling BA. Avios can only book the lowest level. Higher level availability can only be booked with AS own miles.