I think those instructions are mainly to prevent having any interaction or absorption problems, so that you get the full benefit of your dosage. Some people just go ahead and have their normal breakfast and take their meds at the same time. If you lose some of the T4 that way, it will only mean that your dosage may have to be adjusted slightly higher after next blood test. The main thing is consistency in your approach. Some people have avoided the issue by just taking their thyroid meds at night. This can work fine, unless you have some immediate reaction to the T4 med, which interferes with your sleep. This isn't usually the case since T4 is more of a storage hormone that has to be converted to the far more active T3.
For future reference, please note that the best way to treat a thyroid patient is to test and adjust the levels of the biologically active thyroid hormones, FT3 and FT4, with whatever meds are required to alleviate symptoms, without being constrained by resultant TSH levels. Symptom relief is all important. Frequently we hear from members that this requires that FT3 is adjusted into the upper part of its range and FT4 is adjusted to at least midpoint of its range. FT3 is four times as active as FT4 and FT3 correlates best with hypo symptoms. TSH is a pituitary hormone that is affected by many variables and it does not correlate well at all with hypo symptoms. Also, just in case you should incur a low TSH while taking thyroid meds, that does not mean that you are automatically hyper. Only having hyper symptoms makes you hyper.
Sorry if this was more than you wanted to hear, but we hear so many times from patients who are misdiagnosed and undertreated that I thought I should make you aware of all this as you proceed with your treatment.
I think what they mean by no iron or calcium for four hours after levo is supplements. If you wait the hour after taking your pill before breakfast, you can have whatever you want for breakfast.
Soy is basically cattle feed and undigestible unless it is fermented...soy sauce, tempe, etc. Some of us hypos have a hard time with it, others not.
You are going to be dealing with this condition for the rest of your life. My philosophy is to change as little as possible from what you were doing prior to diagnosis. If you notice something bothering you, then by all means, discontinue it. Otherwise, have at it!