Hello,
Welcome to the Thread abc12345!
I am also new here but have been doing alot of research into Special Needs etc.
In reply to your questions then:
TH - no he is not too young for TH. I took my 5.5 year old son there a few weeks ago for the first time. I would say the appt can take around 2.5 hours therefore do take some things to keep him occupied.
I have nearly completed RR therapy for my son. It takes around a year to do however from reading on this thread in previous posts, it doesnt sit alongside TH. This is somehting you can call Robin and have a chat about.
AIT can be done and many parents have done this before TH but primarily because its 2 weeks unlike RR. Im not sure on LWs I'm afraid.
In terms of supplements, the key one's are Omega 3 EPA, Vit B complex and Zinc and Magnesium.
TH recommend (and many on here) give VegEPA from Igennus as it contains pure EPA and no DHA. I give my son this plus also Neurobalance as it contains good levels of Zinc and Magnesium. I need to find a multi-vit that contains B complex.
Have you read the TH book 'Brain Food Plan' by any chance? that would explain alot of the questions you have on the Stairs exercise. Igennus sell the book and the TH website has a discount code as well. Many people have recommended doing the TH programme in a DIY type of way and seeing if you notice changes. That would be via the Book you would need to do this.
What I;'d advise you to do is also read alot of the old posts on here - there are around 4000 posts full of info.
Gluten Free/Casein Free - both are potentially beneficial and some have had success others havent.. Gluten is more difficult as its everywhere so that requires alot of planning and a change in family routine plus school dinners consideration.
EE is part of the TH programme but after a few months - the first parts of the programme is the stairs exercise.
How far are you from TH? I would strongly advise getting the book and reading past posts to get a good feel for TH.
Hope that helps.