On the base attack i can coment mate. . Check out the Table
BAByou have to figure out the classes you have and take the bonus liste there. For the example of lets take the example of a Fighter / Wizard ( 6 / 11 )
We have 6 fighter levels. That will net you a +6 on the base attack.. now if we see the table for a wizard 11 that give another +5 To a totall of +11/+6/+1
how is this calculated well.. Lets say that the player took his first six levels of fighter. That will net him a +6 at lvl 6,then he decides to take his first wizard level. The 1rst level of wizard adds a +0 to the bab as the table listed, So when the player take his second wizard level he will get a +1 for a +7 ( this is at 8th Level ). And so on.. you only have to see if at the current level of the class there is an advancement in BAB. Additionally. the character got an extra attack each time the last attack reaches to a +6 , hence why we got +6 /+1; +11/+6/+1; and +16/+11/+6/+1.
So back to our example of our friendly Fighter/ wizard we see that the wizards has an increase on BAB to +6 when he reaches the 12th level wizard ( 18th character level ), and will got another when he reaaches the 14th Wizard level ( 20 character level )
Hope this serves !!
As for the other question someone else should have to answer..
Cheers