Stuff i know so far -
1. Max EV - 510, Max EV in one stat - 255
2. EV in a stat = 1 point in that stat
3. EVs gained in battle vary depending on what pokemon you face
4. Proteins increase a particular stat's EV by 10 per use (max 100 per stat)
5. Certain berries can be used to decrease EVs
I read somewhere that EVs add up as you battle pokemon but only actually add to your stats as increased stat gains when you lvl up. So when i read that Proteins actually increase your EVs, i got confused as this has an immediate effect on your stats. So now i'm completely confused to how exactly the EVs affect your stats.
For example, if you'd lost track of the EV count on your pokemon or want to change it could you simply feed it some EV decreasing berries and retrain it?
Following from the previous example, does that mean that if i had a Crobat at say lvl 95 with EVs spread out all over the place and i wanted to change to a specific build i could simply erase all it's EVs with berries and then retrain it on low lvl pokemon (so i don't hit lvl 100 as i read you need to get exp in order to get EVs as well) to get the desired spread of EVs and then lvl it to 100 and i'd have the exact same stats as i would have if i maxed it's EVs when it was lvl 15 then lvled it to 100?
I also had a doubt regarding how you get EVs from a pokemon if you used a multiple number of pokemon to beat it. Say i was trying to get EV points in Speed by fighting Zubats in a cave and i ran into a Geodude. I switch to another pokemon to fight it seeing as Geodude doesn't give Speed EVs for beating it (i think). However both my Crobat and my second pokemon get exp for beating the Geodude so i was wondering if they both would somehow split the EVs given by Geodude or if it's just the pokemon that made the kill that would get the EVs?
Also, i read about how gaining EVs work with Exp Share on in a couple of places which explained it differently so if someone could clarify how this works or point me to someplace that has it explained nicely, that would be good
And that's about all i can think of asking...for now :P
Go here.
http://www.smogon.com/forums/showthread.php?t=33832
But to answer your questions more specifically...The items that cost $9800 that give 10 EVs in one stat isn't only limited to Proteins, which boost Atk, there's also Calcium, Zinc, etc. Some take place immediately, some don't. Just keep in mind you can only add 100 in each stat this way.
Also, 4 EVs = 1 stat, not 1 EV = 1 stat (regarding your #2)
If you lost track, simply use the EV reducing berries until all your EVs are gone, EV train again. Shouldn't take too long with Power Braces, Anklets, etc.
If you fought a Geodude, both Pokemon would get 1 EV in Def. If you're not trying to EV in Def, the best thing to do is run away from the Geodude, and only fight Zubats as they appear as only battles where you get EXP count for EVs. Of course, Zubats isn't the best place to train speed, so I suggest you look at the above guide for the best spots.
Exp. Share, both Pokemon get the EVs, it's not split or anything. For example, using your above Zubat example, if a Pokemon had Exp. Share and you use another Pokemon to defeat Zubat, both that Pokemon and the Pokemon with Exp. Share get 1 EV in Spd.
Hopefully that covered everything, but really, the above link is all you need.