At the very beginning layers should be eq'd separately like you said and you should adjust the level of the volume faders to get the desired balance. Experiment with the different levels of snappiness you can get by moving the clap before the snare. Once you get things to sound the way you want start off by merging the layers down to one audio file. What's the point of having 3+ snare/clap tracks if they're being treated as one sound? Condense them down to one and it will make mixing them 100x easier.

There is no need to use a drum bus. The key to getting a layered clap/snare to sound snappy isn't a drum bus. The key is experimenting with the amount of delay between the clap and the snare combined with the transient, decay, and EQing of the sample. You can adjust the shape of the sound by using either logics EX24 or compression.

Also just so you know even if you were to send your layers to a drum bus you shouldn't do it in the way you described. You wouldn't use a "send" because then you just have two layered clap/snare signals playing at the same time. You would assign them to a bus but not via sends. On the actual output of the track instead of using "stereo output" you would change it to the desired bus. THEN you would process all of them together as one sound via adding plugins on the bus.

ahh thanks a lot for the reply. so its safe to say we should always lower the db of individual tracks instead of the master track when trying to make headroom?

Yes. 99% of the time. Unless for some odd reason you're doing it for creative purposes then that covers the other 1%.

I like to layer different hi hat samples because it creates more width. There's not really a consensus on how many you should use. Since learning drums I try to think of it from a drummers perspective by making sure that I at least have one closed and one open hat sample with variations going on between the two. If one hi hat is all you need then just stick with that. If you're making something like DnB music then maybe you should look into a little bit more than just one hi hat.

no they have to sound different when you layer them, so they cover the high freq or mids or lows

Tbh why bother layering hi-hats for fullness when it's just so much easier to find a better sample? I layer for width not for fullness. 

Dmajor/Bminor
Cminor/eb major
C#minor/E maj
Gmaj/Emin
Fmaj/Dmin
Cmaj/Amin

I like to incorporate live instruments so often the best key is dependent on the limitations of the instrument! Those just happen to be the most natural.

It's to my understanding that the volume level of all the tracks should sound cohesive flowing together is it not? In that case... is mastering done in one project session containing all the mixes?

For example if there was 10 tracks on an album.

Would the artist import those 10 tracks into one project file and process them differently  side to side that way they flow together nicely during transitions?

What is overdubbing?

Most places explain it really badly. I don't get it. Could someone clarify?

It depends on how much older you are. If you start with producing at like 10, i can imagine it'd be difficult to properly grasp concepts like compression, EQ'ing and distortion. I myself started when I was 18 and the fact that I was in Uni made it super easy for me to grasp all these concepts. However, I think that if I was lets say 28 when I started, it would've been more difficult for me to work on my creativity. The human brain is more difficult to mold after like 25 years of age, so learning anything will be more of a challenge.

Looks like I got 7 more years to build up those mixing/arranging skills before it's too late and I'm doomed to a life of broken dreams. 

Does it get harder to learn new things the older you become?

Unleash the kraken.