First of all Bt is dominant. Second, if you are told to research side effects on the crop itself, allergens are irrelevant.

You should look up insertional mutagenesis drawbacks (random) that can potentially cause gene knock outs with overall effects anywhere from explicit phenotypic changes to subtle biochemical alterations.

The biggest problem is, the point of insertion is essentially random i.e. you might be in a transposon region, a coding region a regulatory region etc etc.

It’s dominant, one copy will allow production of toxins.

Here is one reference: http://www.ias.ac.in/jgenet/Vol79No2/Jg456.pdf

If you do a Google search for Bt gene, you will come up with more references. You will have to read a lot of material though.

If you want more info go to Syngenta homepage and read their materials. They produced Bt corn.
Here are some basic things you should have though:
Most gain of function mutations (like new foreign gene) are dominant, recessives are rare.
Most loss of function mutations are recessive, dominant are relatively rare.

1. By definition if one copy of the gene is enough to produce the phenotype (toxic to bugs in this case) than the gene is dominant.

2. As I said before, the insertion (what is being inserted – Bt gene) does not matter to the plant. What matters is where it is being inserted within the original plant genome. In that case it matters on plant to plant bases (each specific plant) and you cannot generalize effect (not maize in general). However, whatever effects are possible in maize are theoretically likely to be possible in other plants and vice versa.

3. I do not understand your question: "the gene will have the same reaction in say cotton?" Please, give an example to clarify what you mean.

I think kate is asking whether by genes produce the same proteins in every plant.