Reply in part.
Hello Fire :),
I will reply to a small part of this.
28 consecutive days would be considerably more beneficial than 18 days followed up with 3 days per month for 3 or 4 months. This has to do with the ground the 18 days will have broken and that continuing 10 additional days would take you to a place far deeper than would be the case in discontinuing the fast at 18 days and picking up with fasting 3 days per month for 3 or 4 months... An analogy (though imperfect) might be to a construction project. The job gets set up, all of the scaffolding and all of the materials are in place and there is more productivity each day because all of this can be left exactly where it is so that the project can be continued the next day without having to set everything up all over again. With discontinuing a fast and starting a month later, it's like taking down the scaffolding and taking away the materials... and it takes a while each time to get set up again before you can begin doing the work.
Mineral water is not a good idea on a fast and distilled water is ideal (reverse osmosis is good too). I can't take the time here to go into all of the reasons, but there are previous posts that cover this topic nicely and maybe somebody more familiar with the site can link you to some good posts in this area if you are having a hard time finding them for yourself. Also the same distilled water that is ideal for car batteries is also ideal for human consumption.
Your plan for breaking the fast seems very sound, except one part of it that i don't particularly see as ideal is the plan to introduce bread (presumably made from wheat) which i see as an unhealthy food as well as being digestively binding. I also believe that with digestive issues, you would likely be far better off without meat and that you would do well to eat primarily juicy fruits and vegetables, especially green leafy vegetables. I believe your health including smooth elimination would be far better served if your diet consisted of at least 70% fruits and vegetables.
Something that had jumped out at me was that you had been drinking 4 liters of coke per day which you said was to help with digesting meat and soothing acidity/heartburn and pressure and fullness. I'm not sure if it is in your plans to re-introduce this, but your needs can be far better served in other ways, without dramatically compromising your health. For example, should you choose to re-introduce meat, digestive enzymes would be far more effective than coke and without all of the unfortunate side effects. Also since you don't seem to be aware of this, i want to point out that coke is an absolute nutritional nightmare that wreaks havoc in the body in many ways and this is compounded immensely when we are talking about 4 liters per day. Can you imagine how much better your body (and your health) would be served if you replaced those approximately 1600 nutritionally bankrupt calories per day from the 4 liters of coke with calories from fresh fruits, vegetables and their juices?
You might want to do a google search for "harmful effects of coke" or something like this to help embed this awareness into your heart. It would be good to acknowledge that coke is extremely harmful to your health and to not justify its use when there are far better alternatives. As far as promoting optimal digestion, is there a reason why you haven't choosen to eat a lot of juicy fruits and green leafy vegetables? Establishing a healthy culture of intestinal flora (acidophilus/bifidus) would be beneficial as well.
I hope this was helpful. Blessings to you.