Thanks for checking the game out! Glad you're enjoying it.
1. Yeah - as you level up, you'll be casting spells at higher damage and healing values, so those miscasts will also hurt more when they fail. Same concept for attempting to attune and conjure magic items.
2. An example of this would be if you rolled a 3 on the Action column, which is "Combine". You "combine" more than one thing, so you could roll multiple times on the Object column to determine which things are combined: maybe you roll a 2 and 6 on the Object column, Water and Mind/Senses, which you interpret as gaining the ability to know where the nearest source of water is at all times. This is also very much an interpretable thing, so you could also just roll once for an Object and then use your surroundings for the other object to combine...totally up to the caster and how you want to handle those situations.
Hope these help. Feel free to ask more if needed!