"Just on the new year’s day (that is the first day of the assault) the Federal army lost a total of 1,500 soldiers killed and missing." -- you've been totally brainwashed by Russian propaganda, you don't know anything. In reality, according to Kavkazcenter, the federal forces lost no less than 25,000 men, 2 motor rifle divisions were annihilated, and one tank division surrendered. Victorious Chechen mujahedeen captured Moscow, where they had their way with a certain Alexei. He cannot psychologically recover from the unspeakable things they did to him even to this day -- hence his masochist tendencies.
On a more serious note, as of today, after the fate of all soldiers reported MIA has been established, the tally of 131st Brigade losses during the New Year battle stands at 70 odd men and officers. The vehicles of the brigade's detachment that participated in the battle were shot up from surrounding high rises while PARKED, with no one inside them.
"According to Krivosheev’s book in the first year of the war alone some 30.000 civilians were killed." -- you have to work a little more carefully with sources. This is mentioned in Krivosheev's book, but it's not "according to Krivosheev's book". This number in general is highly suspect, because Russian authorities had no way of calculating the casualties in the republic. Obviously, all members of illegal armed formations are "civilians". So it would be very easy to claim their deaths as "civilian casualties".