When Jackson was asked why did he make Buchanan his Ambassador to Russia, Jackson said "Because we do not have an Embassy on the South Pole".
Buchanan was picked by the Democrats in 1856, for while he had been in National Politics for over 30 years, he had not expressed any comments on the issue of Slavery and as such could be portrayed in the North as opposing Slavery and in the South as supporting it. The next four years he did everything he could to delay the Civil War till the next President's term.
Buchanan was not a "Bad president" but one whose agenda would fit in with today's candidates, standing for nothing and everything good but avoiding the real issues of the day (i.e. Buchanan avoided Slavery in 1856, in 2004 he would be avoiding Iraq just like Bush and Kerry).
Furthermore Buchanan would be attacking his own party members who did address the issue like Buchanan attacking Stephen Douglas (Douglas did not oppose slavery where it was, but opposed its extension, an extension that the south saw as needed to preserve slavery).
Buchanan also sent troops to Utah to suppress the Mormons and lead an anti-Mormon movement NOT because he opposed the Mormon Religion, but because Buchanan saw it as a tactic to unite the Country for a while against a "common enemy". There is some indications Buchanan was planning an invasion of Cuba to achieve the same result but he was NOT re-nominated by his party.
As to Kansas, to keep his southern allies happy he recognized an election that was clearly Fraudulent and when the people revolted against that Government he moved to Suppress that majority. Buchanan continued Franklin Pierce Policy as to Kansas and made sure that the Territorial Governor of Kansas was so pro-south that any crime by a Southern in Kansas (As it relates to Politics) was unpunished, up to and including murder.
This policy had already lead to John Brown's actions killing Several Southerns who he believed participated in the Lawrence raid of May 21st, 1856 (Not to be confused with William C. Quantrill's raid on the same city on August 21st, 1863). It appears Brown only wanted to arrest the people killed, but the action got out of hand and he ended up killing the people he had planned to arrest. Brown did this action knowing that the Federal Army had done NOTHING to stop the raid nor were they making any effort to catch the people who did the raid. Furthermore Massachusetts Senator Charles Sumner was severely beaten by Senator Preston Brooks of South Carolina two days before and this had been telegraph all over the country including into Kansas. The fact that Pierce had done anything about the caning of a US Senator was also known to Brown. While this all occurred during President Pierce's Presidency the Policy of Pierce was continued by Buchanan.
Given this pro-slavery policy of Buchanan many people did not think he would do ANYTHING to stop the escalation of violence on part of the American South. On the other hand Buchanan did everything he could to Suppress Northern Opposition including permitting the shipment of arms and ammunition from Northern Armories to the South throughout his Admin station. Buchanan enforced the Fugitive Slave Act even in states where to be a Slave had always to be proved (The Fugitive Slave Act followed the Southern Rule as to blacks and Slavery, i.e. if you were black you were a slave unless you could prove otherwise, thus no papers you could be sold).
As to Buchanan's following of the Constitution he only did so if he agreed with the Court on what the Constitution said. In his inaugural Speech he said he would support whatever the Supreme Court would decide on the Dred Scott Case (but he included this in his speech only after the Court had already told him how the decision was to go, the Decision came out after the Speech but Buchanan knew its content when he made his "promise" to enforce whatever the Court Decided). This was typical Buchanan, saying one thing but meaning many things to many different people. Buchanan stood for everything and nothing.
Buchanan was a bad president for the above not because he was or was not "gay".
For more on John Brown see:
http://www.pbs.org/wgbh/amex/brown/timeline/Brown and the Pottawatomie Creek Massacre:
http://xroads.virginia.edu/~HYPER/HNS/Kansas/jbrown.htmlhttp://www.ku.edu/heritage/kshistory/pottamassacre.htmlMap of Pottawatomie Creek:
http://www.pbs.org/weta/thewest/places/states/kansas/ks_pottawatomie.htmA history of Lawrence Kansas:
http://www.kancoll.org/books/cordley_history/