Hello Susan,
Welcome to the group. I'll try to answer all your questions without making this excessively long. Bear in mind that we're all different, so this is a generalization based on how most of us are affected. Individual symptoms may vary.
Susan wrote:Intense heat in belly esp. wakes me at nite
Insomnia (wake every hour w/urge to pee)
Bladder infection
Dizziness
Fatigue/weakness
Arthritis in thumbs (coincides w/MC diagnosis)
Increased low back pain (have 30 year history back probs)
Very low pulse rate (bradycardia)
Welt like rash on breast (comes and goes)
Fogginess
The answer is "yes" in every case. But these are secondary to satellite issues caused by MC (and not documented in the medical journals). The first four are caused by a chronic magnesium deficiency (MC depletes magnesium, and so do corticosteroids that are prescribed to treat it). Many other meds deplete magnesium. The last five symptoms you listed are caused by the compromised intestinal porosity (leaky gut) associated with MC that causes all food sensitivities. The welt-like rash is more likely to be due to histamine issues (MC depletes diamine oxidase enzyme [DAO]. Since DAO purges excess (unused) histamines from the body, as DAO becomes deficient, histamine levels become excessive, and cause allergic (usually on the skin) reactions.
Susan wrote:1. What to do for insomnia? Have taken melatonin and unisom w/no improvement) Take Epsom salts baths that help a little) Just like everyone here, I NEED to sleep

If melatonin doesn't help, your magnesium deficiency may be at a severe level.
Susan wrote:2. Is MC considered an autoimmune disease?
Yes, definitely.
Susan wrote:3. Still confused about the progression of MC; does the food sensitivities occur because of the inflammation or were the sensitivities always there?
The chronic inflammation that causes MC causes compromised intestinal porosity (leaky gut). The leaky gut prompts the immune system to produce antibodies against the proteins from which the peptides (medium chain amino acids) that leak into the bloodstream are derived.
Susan wrote:4. Can the inflammation in intestines caused by MC spread to other parts of body, like the brain for instance?
Yes, we're all different, but most of us have multiple inflamed organs (especially digestive system organs) due to the perpetuation of the inflammation associated with active MC.
I hope this helps. You can get a much more detailed explanation from my books, if you want complete details.
Again, welcome aboard, and please feel free to ask anything.
Tex