1) What should a good Iaido be made of.
Presuming you refer to an iaito, the ones I've seen are typically aluminium alloy. There is a company or two out there (Tozando?) that steels "steel iaito," however.
2) Do the CMA, & KMA styles compare to the JMA Styles.
A vague question, and certainly too broad to answer definitively. If by "compare" you refer to combat efficiency, then, yes. However, if you refer to cross-pollenization or some such, then generally not. Again, however, this is far too broad a distinction to make.
The reason Im asking is a few people I trained with in Karate, said that the katas they learned in Tae Kwon Do, etc madew it easier to remember the karate kata.
This is because TKD is strongly related to karate, hence its oft-given title of "Korean Karate."
I wish to study Tai Chi, will this confuse me when I begin my studies of JSA.
If memory serves, Wayne Murumoto practices both Tai Chi and Takenouchi-ryu. You could possibly discuss that with him.
Roberto Valenzuela
Owari Kan-ryu sojutsu (尾張貫流槍術)
Shinkage-ryu heiho (新陰流兵法)
"Be intelligent, but do not be artificially intelligent." --Kung Fu Proverb
"Culture Check: Korean Arts still determined to make indigenous martial history from 4,000 year old cave drawings. France counters by claiming Savaate developed from hunting woolly mammoths before Ice Age." --The Nth Degree