Is there any difference between USCIS and CIS or it's same thing?

There is absolutely no difference between the two.

Is there a "plan B" with the USCIS for a visa is refused ?

How do you know that It was the lawyer who "botched" your case, and not USCIS CSC? I would be careful in making such sweeping conclusions. A Plan...

Hi, My my fiance came to the US with a K1 visa but our families are not ready for our marriage and need more time.

No, if you delay the wedding beyond 90 days, K-1 visa will be no longer valid.

Can GC file for Spouse Tourist Visa ?

I agree. Marriage to a U.S. citizen, or resident is an irefutable proof of an immigrant intent. Her visa will be denied ab initio.

If you are still concerned that USCIS online case status information is not consistent with the letter of denial of your adjustment application...