Short answer - there is really no way to tell until you take care of the ticket and see. Never just throw it away. If you ignore it, they will eventually issue a bench warrant, which will show up if anyone does a background check or you hit the system anywhere in the country. This could affect employment, personal credit for car/home sale/purchase, and other things. There is no straight "reciprocity" between Illinois and California. Illinois is a member of the Non-Resident Violators Compact between 44 states that share traffic ticket information. Alaska, California, Michigan, Montana, Oregon, and Wisconsin are the only states not part of the compact based on the latest info I could find. (Still, a number of bordering states have their own compact, like Oregon and Washington, even though Oregon is not part of the compact.) So what does this mean? It means that while California would not send ticket information to a distant state, they may still receive it from Illinois and it may or may not hit the system in California. (You can read up a little on it here http://www.californiaduihelp.com/california_dmv/drl_compact.asp.)
The best thing to do is see if you can get a traffic lawyer to represent you and get it knocked down to a simple fine or even dismissed altogether. You may even be able to avoid going back to Illinois. It may cost you around $600 or so all in with both attorney and fine, but at the very least the lawyer should be able to plead it out so that there are no "points" on either your license or with your insurance company. (If you throw it away as you said earlier, you will get mandatory points even if you settle it later.) Hopefully this helps.
Yes there is. Each state will report tickets to the other.
Yes
Yes.
There is 363 miles between Illinois and Ohio. There is 1,172 miles between Texas and California. This means there is a greater distance between Texas and California.
Yes. That applies to all states.
Yes there is. Most states will report a speeding ticket to your home state and it will be posted to your record for insurance increase purposes.
It probably differs between counties.
About 2,080.
my house
There is no reciprocity between the lawyers of the two states.
about 1700
there is