Well . I have been fighting the drums sounds for sometime now.  I guess I am a slow learner. It was mentioned that a fast easy way to fix up our live "studio" drums was to get some drums samples and add to it (Marino I think).  I wasn't sure what he was talking about so I did some research, one of the guys on here mentioned  EZ Drummer.. I checked it out, liked what I saw, and purchased the starter ,plus add-on library of sounds.  This is by far the easiest freakin way to get good drum sounds.  I can tweak the kit to the way I like., set the velocities and pans in a super easy fashion ( I know that some of you have been using this for years but it is new to me).  I was able to get a very decent drum track down (complete with fills ect.) in about 1 1/2 hrs out of the box. 

 I would recommend this software or any that is similar...... software made just for the purpose of putting down excellent drum tracks.  It is so easy and  the sounds are great.

 I will put some stuff up (on the amp) in the near future.

But I have always been a little skeptical on these drum machine type things.
What kind of a sound do they produce?
Can you adjust the beat to whatever you want?
Do they sound fake or unrealistic?
And wouldn't an actual drummer push your music over the edge?

I've also just started using EZ drummer.. it's the dog's hairy's as far as making drum tracks for me.  The kit is configurable, mic 'position' can be changed, and it can accept any midi drum track if you've already got one made.
This software also has 'real' drum beats (played by a pro on a digital drum kit, with just the beats captured); these are organised into various different styles, speeds etc, and are 1, 2, 4, or 8 bars long - each beat has up to 20 variations.
I don't often sing the praises about a bit of software, but I'm well and truly with Toasted Goat over this one.
As far as your questions are concened:
- They produce different sounds depending on the kit chosen, but I have the basic rock and a latin set.
- The beat can be adjusted however you want.  You can take the sample beats and then play around with them too
- The sound is recorded from a real drum set, so it sounds spot on.
- I have a real drummer, Toasted Goat has a real drummer.  The dynamics of a live drummer are going to be better (if the drummer is any good!) - but recording drums is a pain, and it takes the right gear and time to mix etc to capture not only the dynamics, but also the sound.  This software is a really good compromise.

Mix the 2 .. thats what I was trying to say .. our drummer played the parts.. then I added a midi track for the snare (cause our recorded one sounded bad) and lined the hits and velocities up with each snare hit he did and "Bam" a much improved snare drum track.  Also kicks or any other parts you might need to touch up .

 I got this idea from reading stuff about Mutt Lang and the tricks he uses to fix or help a mix.

I also use the EZ Drummer software for laying down drum tracks for my personal music writing . to bring along ideas for the bands new songs.  There are other drum softwares out there that are probably as good or better,  like BFD as an example ,  but for my price range EX Drummer was the choice.