Timing/phase-advance for creating a memory task

Hi everyone!
I am trying to create two experimental memory tasks using a Qualtrics survey. However, I have a few questions that, if at all possible, need to be solved using a custom code:
1. The task involves participants being shown letters and math equations to be sequentially presented for a limited time. I was wondering if there was a way to control the time in which the stimuli is presented and to phase advance a question whilst there is text on the screen? I have found the timing/ phase advance option but I am unable to overlap this with text. Is this possible?
2. My task also requires participants to respond with certain keys to answer the math equations. For example, if the equation is correct, they should press 'Z', and if it is incorrect, they should press the '/' key. Once the keys are pressed, I would like the screen to advance on to the next page/question. Is there a way to do this?
3. I have also been unable to find a way to remove the forward and back arrow on the question screens. I would like to remove this function so subjects do not have the ability to move back and forth during the task (unless being required to do so). Can anyone help me with this?
Thank you in advance!!