Re: Layering Kick Drums/Frequencie...
1. On the channel strip for your kick tracks (found in the Inspector section on the left of the arrange page) is a rectangular box with EQ qritten in it. Double click the box to open up the Channel EQ.
There are more EQs to choose from, and you can find them by clicking on any empty slot directly under the EQ box. Choose your favourite EQ from the drop down menu.
I'd reaaly reccommend getting hold of Logic 101: Core Logic, and watching it in full. You'll understand a whole lot more about Logic from watching and listening to Martin - epecially where to find these essential tools! Check it out.
2. Layering a kick is provbably best done with the Channel EQ. You asked about combining 2 kicks, so you'll need one channel EQ for each, one with a high cut filter - to let the low frequency kick through, and one with a low cut filter, to let the high frequency through. Choose a steep filter slope for each.
Its fairly simple once you understand how the EQ works - basicly you want to let though as much of the deep frequencies of the low kick by opening the high cut filter, and close it just before the frequencies of the high kick begin.
Likewise, move the low cut filter slope on the other kick around until you're just getting the high frequencies you're after. There should be a small crossover of the two filters so you don't end up with a dip in the frequencies between the two kicks.
If none of that makes sense, you'll understand better by doing it! Its always a bit trial and error, and you'll know what sounds best.
A couple of things you need to watch out for:
Because the two kicks are different samples they may be out of phase. You might have yto get a bit hands on in the sample editor to trim them up so the start points match exactly, and even then you might find you have to choose anoyther kick that goes better.
The two kicks might sound great separately but together they might sound rubbish.
Also, there might be a better way to achieve boominess using just one kick, mayvbe by using compression and boosting the EQ at about 45 - 60 Hz.
You might want to layer the kick with a 'sub' sine wave instead - I can tell you more about this later if thats something you want to try.
And what you have to keep in mind is that there are always two instruments hanging out in the bottom end - you need to think about the bass as well! There is no point in filling the whole spectrum under 100 Hz with boomy kick if it means you can't hear the bass.
Anyway, take a look at the channel EQ and have a go - if you need help with how the EQ works or what filter slopes are all about, write back!
And definitley check out Logic 101 Core Logic.