I have a Daiwa Exceler 4000 reel with Sufix Superior 15lb. mono on it and last night when I was fishing with it I kept hearing a sound like something was hitting somewhere and as I watched it the only thing I could see making contact somewhere was the line where it goes through the first guide, when I retrieve it the line spins around and hits the sides of that first guide...is this normal?

Yes - not unusual and will vary based on exact specifics of the rod (guide size and spacing) and reel (esp. spool diameter)....fish on

Yes, for 15 pound test mono on a spin reel.  For mono I never go over 10, usually 8.  If I need higher pound test than 8, and I do on most setups, I use 15 pound high quality braid.  Casts like a dream.  You may want to use a flourocarbon or mono (mono for sure if you cast surface lures) leader.  You'll need to learn a good braid to leader knot.  Most use double uni which is reliable and easy, but it won't go through micros well.  Some don't use a leader.  Braid does need better line to lure knots than mono or FC, the palomar is what most use, but there are others.  

that's the coils of your line going through the guides , that's why a lot of people (myself included ) are switching to braid as the mainline , with a flouro or mono leader .

  that's the whole reason for the microwave guide system , a funneling first guide to small guides to take the coils out of the line as it passes through the guides making for smoother , more accurate , & longer casts ...

I don't think microwaves will handle 15 pound mono all that well.  They work pretty well, but they are not magic.  Even with 8 pound mono on one of my rigs, there is a "buzz" of the line through the guides on the cast.

Yeah, still getting used to/practicing with/gaining confidence in my bait cats setup. Hopefully soon I'll be fishing the larger line diameters with that but right now I want to go with what I'm comfortable so i can catch some fish :D.

Heavier mono definitely makes more noise.  I can vividly recall the sound of my dad's 14# line when cast on his 7-6 Garcia rod with a Quick 5000 reel.  I had a smaller reel, so was limited to no more than 8# mono.  The sound was very distinctive.

I don't have any larger spinning reels. A little too heavy of line, and generally speaking, the extra noise is from me saying unpleasant things about the issues I'm having with it.

 

I am not a fan of braid, but if I had to use heavy line on a spinning reel, it would be braid with a copolymer leader.

15-20# braid will probably solve your nose issue. But all line makes some noise. Use silicone lubricant on your line and line guides.