Apparently the issues at stake were worth it to the Confederacy since, as far as I can determine, more Union soldiers were killed than members of the Confederacy. Death toll per the Encyclopedia Americana:
- United States: 360,222
- k. in battle: 67,058
- d. of wounds: 43,012
- [Total battle deaths: 110,070]
- Confederacy: 258,000
- [TOTAL: 618,222]
Civilian deaths are estimated at 50,000 total (both sides). Non-battle deaths came from a variety of sources, most notoriously, deaths in prison camps operated by both sides, largely from starvation and disease.
I don't know about shelling civilians, although I suspect that both sides did that to some extent. Suspension of habeas corpus was definitely done as permitted by Article 1, section 9 of the Constitution in case of insurrection. Other than DiLorenzo, I haven't found details concerning northern secession. Presumably nothing came of it.
On the issue of my "revisionist" theory that slavery was the most immediate issue leading to secession, I offer the following:
Those sound like pretty clear statements to me. The "revisionists" are those who now try to downplay the central role of slavery from the very beginning of the secession movement. (quotes from
http://sunsite.utk.edu/civil-war/reasons.html) For those arguing these issues, I think it only appropriate to include sources for claims made.