Ha... you've been used to flying sports models havent you? Welcome to the world of scale aeroplanes... a totally different ball game and a complete different technique mindset.
Yep it wants to take off at a very low throttle setting, know why? Because as a model its massively over powered compared to the full size.

Learning to taking off a Cub with finnese is one of the great RC aeroplane milestones!!! So enjoy the learning experience.

As you're experiencing trying to do it fast dosen't work. You Must go very slowly on the throttle. If you are getting airbourn at anything over 1/3rd throttle you'll going way to quickly.
As you have seen, it wants to take of it's self at a low throttle setting... it's either stalls, or you slam open the throttle and it snaps...bummer.

It has to be one slow constant movment, best practiced in very little wind to start with.

Taking off left to right with youself in the middle: I be positioning your sized aeroplane at least 20m to my left. Start advancing the throttle to make it taxi, advance a little more to a faster taxi, alittle more to an fast taxi letting the tail raise, advance again to break ground infront of me, advance again as it's getting airbourn, advance again to fly away with authority, advance again to you desired flying speed... this is done in one smooth transition, get the picture.

Forget about holding in up elevator as you take the run. If it's nosing over it's because you've used to much power... infact done correctly you'd be needing a little down elevator!

Rudder... Cub? Damn it's a sensitive mother...they can start swinging this way and that can't they?
The key again is speed or in a Cubs case, the lack of it. Any swinging on your take off run basically case for a abort! Forget it and start again. You must watch the aeroplane very carefully and input (ease in) the rudder the MOMENT you see the slightest deviation from the center line. You are new to the hobby so the aeroplane will be ahead of you 99.9% of the time and thats not a good place to be when it come to rudder correcting a Cub. Thats why we have to practice, to get to understand the aeroplane and learn it's ideosychrosise(spelling) so we'll be ahead of it!
Enjoy the proccess and good luck.