You're welcome Marcos.
I didn't pick up the center column, so I'm afraid I can't help there. I strongly suspect it would fold up fine with it though. But that's just a guess.
The free bag is fine for what it is. There's not a heck of a lot of padding, but I don't find that a bother. In the name of full disclosure: I'm a Domke / Billingham user, so I tend to think of padding as over rated.
It's far from the best bag out there, but it's decent enough. I suspect if anything gives out it will be the zippers. Time will tell. The side pocket is large enough for me to keep some allen wrenches and a nodal rail in there. I'm pretty sure that if you wanted to spend the money it wouldn't be hard to find a nicer one.
In all honesty, I'd never seen a Feisol tripod in person until mine arrived. I was VERY pleasantly surprised. Even though I don't own a Gitzo, I've always really liked (and coveted) them. And I still do. But now that I have the Feisol I'm no so sure they're worth so much more money. This is back to that old seeing if I have problems over time thing. I can see where it might have issues where the legs attach, but not being a structural engineer I'm not sure there's really any sort of potential problem there.
There are a couple spots where it looks more poorly built than the Gitzo, but does that mean it's weak there, or that the Gitzo may be a bit of overkill? Dunno. From all user reports I've read on the Feisols, I don't think there's going to be an issue.
It's been perfectly stable for my needs so far. I think focal length is more important than weight - it's actually quite hard to exceed the weight rating of these things. Ten Kilograms is a LOT of grams for a camera & lens. The two largest lenses I've used it with have been a 300/4 & a 70-200/2.8. No problems, no worries.
I wouldn't hesitate to use a 400/2.8 on it and if someone want's to send one my way I'll gladly write up how it works out. 