just have to ask about shoulder rest. Is it necessary and how much does it helps?? How should I know what size to buy,and should I buy it at all?

There's a tip in www.violinmasterclass.com you can check it out there. But as for what I know, shoulder rest is not required, it depends on you if you willneed it or not. those who have shorter neck sometimes doesnt need one. sometimes they just use a piece of cloth or a sponge so that the violin will not slip in the shoulders. What is important is you are comfortable with the position of your violin,

I personally do not use a shoulder rest at the moment- I used to have to, but thn I upgraded instrument size and neeeded to do with out it, and I got used to it. It really helps, though, especially with shifting, because none of the weight rests in your hand. I will probably start using one again as I'm do more difficut music.

I find it pretty painful if I do not use one.. but it really is just a personal preference

I started to using the shoulder-rest weeks ago as a result of a friend's suggestion, and have accommodated myself to it now.
According to him, it depends on the length of the neck.

The shoulder rest really helps me... esp. with shifting it is a lot easier. You can get used to playing without one though too.

I like shoulder rests. A lot.
I think that most violin pieces with much position shifts are virtually unplayable without using a shoulder rest. You go easier on your arm too if the weight if the instrument isn't totally on your thumb, but also on your shoulder and chest.
But... If you prefer 1:st position music it's totally a question of preference. And the sponge is fine anyway, if your neck is short.
And baroque violinists don't use shoulder rests either, so it's really up to you. But I would suggest using a shoulder rest anyway.

Thank you very much!!! i decided to take a shoulder rest and try it!!! thank you sooo much again!!!