Woah, way too many questions to answer on a blog post like this. You simply must sit down with an attorney and go over the initial MOU and the modification to the MOU. If he is going to try to bully you, you are not going to get anywhere by simply proceeding on your own - as I think that you have already found out. An investment in an attorney will be well worth it and might just be the best decision of your life.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
You cannot force the other parent to exercise parenting time. If he is refusing to exercise, you will probably need to propose that he not have parenting time and child support should be modified accordingly. If this prompts him to work with you, you can work on a more moderate parenting plan.
If this is important to you, you really should retain an experienced family law attorney to assist you.
You can reach Harkess & Salter LLC by phone or email. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
You may want to file the stipulation you already have, get an order from the court approving it, and then file a motion to modify child support. But you really should gather up all your paperwork and sit down with a competent family law attorney in your area and discuss your situation before doing anything.
www.karlgeil.com. This answer is provided as general information about a legal issue, is not legal advice specific to a particular case, and does not create a lawyer-client relationship with the person asking the question.