Yz2-newbe questions

[Lowie]

Hello all.
Getting back into RC-racing after some years "off"
Getting an YZ2 Ca for my boys. And I do have some questions.

Could someone explain me the difference between the FLAT front arms and the GULL-ones? In this I mean: in what circumstances/trackconditions would one use one type over the other?

It seems there are quite some possibilities in using different rear arms, hubs, axle-lengths ... all very confusing. For now, I guess I'll tsick to the parts and dimension sused in the manual.

The manual also shows that one can us shorty lipo's but also a saddle pack.
As I still have some saddle-packs layong around I would want to used those.
... but then I notice that on all pictures I only see the shorty used.
What are your thoughts on using a saddle-configuration?
Is there such a big range of disadvantages that this is a big no-no? ... keeping in mind that the car is intended for my boys who are also rather newb's

We will be running on (Belgian) astro tracks. Any thoughts on which (Yatabe) springs I will need for the suspension? I want to avoid buying the whole range of springs from which most will never been used, as happened to me with my dex410.


To end: I understood, by reading through lots of comments on this and other forums that I could use:
* some spare A-arms (also called wishbones around here I think) Front and Rear
* a front bulckhead
* hinge pins
* ...


Thanks in advance for all info and feedback!