Welcome Truccka
Its definitely a good hobby to share with the 'kids' (mine's 16 now)
As Lozart said, there are several reliable makes to get started on. As well as G&G I'd suggest to look at SpecnaArms 'Edge', CYMA and JG (JingGong)
Sorry, no experience with Dye i4 but suggest to get some 'CatCrap' (yes terrible name). It does help and you can use it on the rented mask in the meantime.
Helmets are not a must but as well as holding a camera they can save you from a nasty bump if you fall. Especially if running a lot.