+1 for magnesium and vitamin C. I've not noticed any cramping with citrate and it's absorbed better than oxide or hydroxide.
Kind of depends on how well you handle fiber. If it's well then the flaxseed and psyllium might be useful for a 'bulking' action. For a more softening action mag and C are good.
Definately get some probiotics in. Appears to be highly individual which brands/strains help people with constipation but they are likely to be doing some good regardless. Then there are things like sauerkraut and kefir.
The occasional plain water enema won't do any harm, and can be quite relaxing.
They do work but I'd put herbal stimulant laxatives at the bottom of the list due to their potentially abrasive and dependence properties.