名媛直播

Hi, can somebody please advise on the following.
I got given a Chinese Elm 名媛直播 tree as a gift, not previously having any experience with plants, let alone 名媛直播.
The little tree was apparently bought from a garden centre. It was fine for a couple of weeks and then the leaves started turning yellow and the base of the trunk looked discoloured. I did lots of research and followed different advice. I finally went on to a reputable 名媛直播 website and purchased everything I needed to repot (including soil, pumice, moss, biogold), etc. Anyways, in the process of taking the plant out of its original pot, washing & inspecting the roots close up, I came across what I can only describe as masses of cotton wool, all entangled within the roots? I gently removed it all without damaging the roots & threw most of it away, but kept a bit to take pictures of. So, my questions are as follows; 1. What is this, could it be cotton wool? 2. Is this normal? 3. Should I have removed it all? 4. Could this have been the cause for my little tree looking poorly? I would appreciate any advice that can be given. Thank you.

Looks to me you have just pulled pieces off the roots.

The reason your tree got yellow is probably a combination of moving the pant from one location to an other, together with a different care regime. Repotting is hardly ever the answer. The plant was happy and healthy in the soil when you got it. More likely, you do not really know how to care for it, which is why the tree gets stressed. Now it is important to care for it properly, not letting it dry out, not drowning it. And to give the plant a couple of weeks to get settled.