Fungal spores from the air attach to the soil surface and they sometimes find it a good place to thrive, as it is made from natural ingredients, it is constantly moist and no fungicides are used.
Here you can find more information about mold and a tutorial on how to remove it: Growing with your indoor garden and notice mold? Read this! – Click & Grow EU
Mold on the surface of the plant pod is quite common and is harmless, and does not harm seedlings with true leaves. However, if you wish, you may remove it and cover the open soil area with cinnamon powder. Please read about how to treat mold here.
Regarding Mini Tomato, the white mass is healthy roots. However, the pod should have been thinned in the seedling stage so that the one remaining seedling would have all the nutrients and space to thrive. If you wish to replant it, please plant it a few cm deeper than the current soil level. There are very nice and healthy root nodules visible on the stem. As soon the nodules have nice firm contact with fresh moist soil it will become a healthy root mass and support the plant with water and nutrients.