You have enough time this growing season to cut, dry, and root columns cut from that plant. This will be enough time for the columns to get some roots going before they go dormant over winter ( assuming your location is not in the lower tier of states or other similarly semi-tropical locale). Rooting columns shouldn't get much water anyway but be sure to get the soil good and dry before you bring them indoors for the winter. Wet soil and columns lead to etoliation and sometimes rot.
You would not do wrong to give the whole pot a good watering a few days before cutting. But after cutting keep the cuts fairly dry until they establish some roots.
Two inches above the soil sounds good. What you need are some areoles left above the soil for pups to come out of - unless the plant decides to pup from the base.
I don't know if there is a rule about how many columns you can cut from a clumped Trich. I like to leave enough column(s) left in the clump to photosynthesize and keep the rest of the plant and roots healthy. I haven't really thought about the math of this before so I'll say you could cut 50% of the mass of the pot and be confident of the plant staying strong.
Or to say it another way, this time specific to your pot, you could whack the short one two inches above the soil and each of the taller columns halfway up.
Then you could probably cut the two longer cuts in half and have a total of 5 new plants to root. The two taller ones each appear long enough to get at least 2 six inch sections to root. Six inches being what most of us consider a safe minimal length to root.
Also - pay attention to which end is up when you root the columns. It's an easy mistake to make but planting columns upside down really messes them up. They have to spend a lot of energy reorienting themselves to the sun and soil. This energy would be better spent growing roots. I've heard of columns being lost to this error.
Edited by pharmer, 09 August 2017 - 09:01 PM.