Biggest issue with horse bathing is making sure to rinse REALLY well, don't leave shampoo or conditioner in the coat. (some leave-in conditioners are okay for mane and tail, but I find most can get greasy and attract more dirt anyways). Stuff left in the coat can cause skin irritation.
For white/light horses that require frequent bathing, this is my best friend:
It's a lawn/fertilizer sprayer you attach to your hose, you should be able to pick one up at any hardware store or garden center. Obviously, don't get pre-filled ones with fertilizer in them! Pour a shampoo concentrate in the jug, most have a dial on top where you can adjust the dilution ratio, attach to hose and off you go. I spray down with straight water first, then the shampoo/water mix, stop to scrub with a bathing mitt and use straight shampoo on any areas that need it, then rinse. To me it's a great time saver, and since I have a mostly white horse that likes to be green, and I have a lot of feathered fetlocks that need frequent bathing, I use it a lot.
For the curries, I do what ponyjocky mentions and whack it against a wall or post every few strokes to knock the dirt and hair out.
I have a bay and white paint also. My curry is always dirty, just tap it on something when you see you're just moving the dirt around instead of removing it. IE: pavement, fence, your hand.
When bathing its nice to start at the hoof/leg so the temperature doesnt shock them. I wet my horse well, shampoo his entire body ( I use mane/tail shampoo for body and mane/tail) then I use Goop, see the post about getting a yellow horse white . You can buy it in the automotive section, its for mechanics to wash their hands, but I use it on mane and tail and any stained spots.
As far as picking out the hoof, google the anatomy, its important that you clean it properly and that you have confidence. Any lack of confidence MAY end of causing your horse to not trust you, which can turn into disrespect. Not saying it wil, but it happens with newbies. Find someone knowledgeable and see if their willig to work with you, it'll help build your confidence tons.
My TWH is black except 1 foot, a star, and a snip on his nose. He's a dream to bathe except the white foot LOL. I use my shampoo and conditioner (Drives the bf wild that I use an $8.00 bottle of conditioner on him hehehhe) and just make sure to rinse well. PLEASE pay attention to the sheath area and between his hinds. I have seen so many people neglect these bits on their guys. And yes, please wash his butt :)
As for the hooves, seriously, youtube has a couple great videos, just look up cleaning a hoof. NOTHING beats having an experienced person show you how though.