Too true, on both counts. As I stated earlier, making war on Texas would be akin to making war on an entire country of angry, armed people. The odds would not be in favor of the US, hence, they wouldn't do a thing to try and stop us from seceding.
The same holds true for many other US states. Heaven help DC if several states decide to withdraw from the union simultaneously. That in itself could force the federal government to back down and accede to our demands.
This already happened once before.
South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, Texas, Virginia, Arkansas, North Carolina and Tennessee seceded from the United States between 20 December 1860 and 8 June 1861.
They were crushed in 4 years.