I'm not by any means a high elo player, but I've been jungling Shyvana on and off since mid-Season 3. I guess, I'll just comment in order as you wrote.
Jungle Itemization
I'll start with the jungle items. To be honest, 9 times out of 10 you're going to be building either Stalker's Blade or Skirmisher's and which one you get is pretty much determined by whether or not you can make good use of Skirmisher's against the enemy team. Tired of Rengar running in and out of bushes? Pick it Skirmisher's. Can't really stick to the enemy team to make use of it because of high mobility? Stalker's might be better.
I don't think Trailblazer is a bad item on anyone (despite recent nerfs), but rather I don't think it's really needed in this case. Shyv has amazing clear times, and can stay pretty healthy in the jungle past really early. Sure your first clear hurts, but that's with almost everyone. I started taking 9-21 instead of 21-9 and noticed a pretty nice diff. Blue side, smiteless on krugs and use your smite on red early to get your hp back. Pop a pot on krug if need be. Purple side, start toad (smite this or blue early up to you), blue, wolves, then smite red (should be back up in time). If red is down, smite krugs and clear np. Poacher's is almost always a waste of gold (unless you're Nunu or Shaco).
Devourer is perf. Stack it and make them cry.
Full Itemization
First Priority is getting the gold for your devourer enchant. The sooner you can stack, the better. Tabi or Mercs, is up to you. If you go Mercs, shoot for Wraith Elixer later on for sustain since you already have some tenacity (sure it stacks, but do you reeeally need it?) If tabi, grab Iron Elixer. I usually rush botrk second item because 1) sustain, slow, synergizes with your q, and 2) Between this and devourer that's usually all the dmg you need to make people cry. After these two items, go ahead and tank up. Sunfire is ideal for the dmg, kit synergy, jungle clear, split push strength, and nice stats. If AP champs are the issue atm, grab giant's belt over armor, otherwise just grab whichever you can afford. After that, grab SV. Usually you want this because it's another sustain boost on top of nice stats. Last item is player's preference. You can grab another tank item like thornmail or warmogs (or more armor/mr), or you can pick up some cool damages. I usually go triforce.
You could couuuuld build raw dmg, but it's much more fun to laugh in their faces as they struggle to kill you in all your tanky glory, then roar just cuz dragon form. After all, you can melt just about anyone with a stacked devourer's and botrk alone. (Also, dying fast is no fun ;-;)
Shyvana CC MIA QQ
True, Shyvana lies within the realm of the easily kited, and it can suck balls sometimes. If you're against a team where you think it'll be a big issue, grabbing Stalker's is A Okay. You'll also have botrk passive. Personally, I take exhaust over flash and use that to make ganks 1000 million times more effective, and just use my ult to close gaps. Also comes in handy for lategame team fights and jungle wars. Good thing you can farm it back, huh?
Wit's End
This will forever be a strong item on Shyvana. The thing is, it's mainly a source of atkspd, and you already have two of those items in the build (devourer enchant and botrk). If you're okay with sacrificing the active and sustain from botrk, then sure. Otherwise, save it for the Top lane Shyv mains.
Hope this helps.