bike maint.
I'm no expert here, but for my money use only water, a small brush and a toothbrush (not yur own) for those hard to get to areas. Don't use any soap or degreasers because it removes grease and lube from the areas that need them most (sealed bearings and such). I only a light coat of lube on my chain and don't use any on the chainrings and cogs because I feel it attracts dirt and grime and causes wear, what's on yur chain should do the trick. Cables are cheap so I tend to replace them once a year to keep her shiftin' easy, and regularly inspecting the frame for wear and cracks is a very good idea. If you've got dual suspension make sure the pivot points aren,t wearing, loosening and stay lubed.
As far as noises when riding, every bike makes certain "normal" noises when yur riding, know what's normal for yur bike and be alert for the abnormal ones as that'll give you a heds up that something may be goin' wrong. Also, smooth shifting will prolong the life of yur drivetrain immensely, shift early, before you're putting a lot of pressure on the pedals, or let up on pedaling until the shift is complete. Doing that, I really only replace my drivetrain parts about every five years, and I'm a big guy (225 lbs). A lot of guys are replacing drivetrain parts farrrrrrr more often and I rarely have shifting issues due to wear.
Anyway, that's all I got, and I've been running the same bike for over 11 years now, so I guess that says something seeing as I'm my own wrench. One more thing, if u buy high end, it will always be high end. If u buy cheap or mediocre, it's more prone to being crappy or wearing out quickly or just plain breaking on u. Good luck and have fun riding.
PS- I'm sure you'll get plenty of varying advice on this topic, so soak it all in, then do what works best for u.