The Hazel itself can technically carry up to four shield boosters if you've got the right configuration. Traditionally, the Hazel can mount two shield boosters on its arms and one on the movable booster pod on its backpack thrusting unit. The Advanced Hazel features a movable booster pod that can mount two shield boosters parallel to eachother and traditionally doesn't carry any other shield boosters on its arms. You could, however, combine the two traditional loads and give a Hazel two shield boosters on its arms and equip the double-mount on the backpack for a total of 4.
As far as the Gunpla issue goes, if you're familiar with Bandai you know that you never get EVERYTHING in one set.
The HGUC Hazel Custom includes 1 Shield Boosterand 1 normal combat shield
The HGUC Advanced Hazel includes 1 Shield Booster, 1 Advanced shield booster (almost identical to the shield booster) and 1 normal combat shield
The HGUC Hazel II includes 1 shield booster and 1 normal combat shield
Although these kits only come with their respective equipment, this doesn't prevent the purchaser from equipping additional shields. If you were to pick up more than 1 Hazel kit, you could use the shields from those to add to another kit.
As far as your "picture in a mobile armour/transforming like pose with 3 shield" claim, the Hazel is not a transforming mobile suit. It can simply turn the shields on their mounts to face different directions. That "Transformation" is the Hazel's "Final Form".
The image you're referring to the Hazel being like the Strike Noir is sort of inaccurate, since the Noir has no shields (I'm assuming you're referring to the Noir's swords stored on its backpack) and the Hazel's shields mount on the arm, not the back.
For the record, I haven't seen Advance of Zeta either, its not an animated series as far as I know. Advance of Zeta is a photonovel-based story from Dengeki Hobby Magazine and has also started to be released in Manga format.
::sigh:: I feel like I abuse my promotional abilities, but if you want to check out more about AoZ, look through these websites:
Titans Test Team Arc
Advance of Zeta @ MAHQ
Advance of Zeta @ MechaScientific
It still amazes me how much promotion AoZ has gotten in recent years and how many people have purchased its merchandise and yet, it bothers the ever-living snot out of me to see how little people still know about it! Especially if you're part of this forum where there is actual information about this...
For the record, it seems Deus is faster at typing than I... I realize it appears that I have repeated half of what he has said but I'm simply too tired right now to go back through and hack out what he has already covered.