Hi there! I'm glad you joined us! Congratulations on your choice of a quaker companion!
Quakers are one of my favorite species. Quaker personalities can vary greatly but they do have species specific traits. They are scary smart and for small birds, they can present some challenges. The noise and slightly spread wings you mentioned in your other thread, if accompanied by head movement is called quaking, some quakers do this well into adulthood. Since your quaker is only three months old and recently weaned, he or she could be begging for food. A warm spoonful of cooked sweet potato, brown rice or oatmeal in the morning and again in the evening would probably be appreciated. As Mark/Birdman mentioned in a previous thread, don't serve hot foods, just a little warmer than room temperature is best.
Quakers learn fast and most respond well to training. Quakers tend to be defensive around their cages, in the right situation they can deliver a very nasty bite. If you allow them to bite at a young age, the behavior can get out of hand before you know it. In my experience, a time out perch on the front of your quaker's cage is the quickest and most reliable way to train a quaker. Consistency is the key, calmly return the bird to the perch for five minutes each and every time he or she bites, quakers love drama, if you reward them with drama they will repeat the behavior to get the same reaction. Three time outs is my daily limit, after three offenses in the same day, they go into their cage with the door closed.
Your cage is a great size for a quaker as long as the bar spacing is no bigger than 3/4 inch, that's the max for a quaker and I would be cautious about 3/4" with a young quaker, they are, as Birdigirl mentioned, notorious escape artists, if you forget to latch, clip or engage a lock on their cage, they will notice and be out and about without permission.
Your little guy are girl at this age will probably be curious enough to try just about any toy you offer. Paper shreddables, soft wood, straws, sticks, foot toys are all popular. Knotted strips of leather make good quaker toys, most quakers will make a game of untying the knots.
Not all quakers talk, those that do, speak clearly and mimic every noise they hear. If you have sensitive guests, you may want to sensor language used around your quaker, they have a real knack for picking up words you or your friends and family may not want to hear.
Enjoy the journey and please share your adventure.