I'd be interested in knowing what sources you researched, as IME most will provide almost identical information :-)) There's several different species of clumping bamboo but the Fargesias tend to be used very widely as they are commonly available, tend to be some of the most cold hardy and come in various species and cultivars that offer different mature heights and habits.

1. No, they are not invasive and you do not need a root barrier to contain. That's why they are considered 'clumping' rather than 'running' bamboos. They do not have the very aggressive, monopodial rhizomes that can produce culms at great distances from the mother plant. Rather, they have a sympodial rooting system, producing dense clusters of new growth, with a slowly increasing overall clump size. This is the same way many other types of popular ornamental grasses grow, like Panicum or Miscanthus. And bamboos are just tall growing, woody based ornamental grasses :-)

2. How many you would need to fill that area depends on the specific selection, what kind of growing conditions you can offer, how big your plant budget is and how long you are prepared to wait for full privacy screening. It won't be immediate......even running bamboos take a few seasons to fill in.

3. Height again will depend on selection. Once established, each new culm will achieve a mature height in a single growing season. So yes, it grows fast.

4 &5. It is both deer resistant and evergreen.

The American Bamboo Society is an excellent resource. And of the commercial sites, Bamboo Gardens provides very good information on the types of bamboos and preferred growing conditions as well as answering a whole raft of bamboo growing issues. Both of these are my go-to sources for info on bamboo.

I actually looked at american bamboo society and some bunch of other sites and some of them say you need a barrier and stuff. Lol if this clumping bamboo has all the advantages over the running one, what makes some people choose phyllostachys over fargesias?

"...some of them say you need a barrier and stuff"

I've been growing bamboo of all kinds for close to 20 years and I have yet to come across any informed web site that will tell you that you need barrier for clumping bamboo. The base of a clumper will get somewhat larger each year, but it's not going to go anywhere.

Why do people choose Phyllostachys over Fargesias?

Because they like the different look of the plant, the different culm colors, the greater diameter and height of the culms, or because they want something that spreads.

How fast does it generally grow upwards?

Not at all once a culm comes up. With all bamboo, culms usually shoot and reach their full height in at most a couple of months. Once they reach their growing height that season they will never grow taller. But if the plant is healthy and happy, it will put up successively taller culms each year. It will take several years - maybe 3 to 5 -- for your hedge of clumpers to fill in and achieve more height, so if you want results pronto you will need to plant them pretty close together and have them be of a size when planted that is at or near your minimal acceptable height.

I have a maybe 10-year-old planting of three Fargesia robusta (don't remember cultivar, if it was one) in zone 7a near Washington DC. They have died back to the ground in the recent polar vortex winters. No sign of running. Haven't noticed any deer damage.

suburban, really surprised your Fargesia did so poorly from those winters. I am about 4 hours northeast of you and these did not suffer a bit; and I do remember that cold. Positioning is really important with these and my grove does get protection from a lot of wind and excessive sun (winter and summer). Might be the species difference too.

Mine aren't shielded from wind and sun.