At this point design constraints are pretty loose, but in answer to your numbered items:
1. None
2. About 1 ft, but not hard - could be greater
3. No requirement, but practically I think maybe 20 in.
4. No, environment is controlled.
5. first load = 30000 lb w/ 1 in. deflection, 36000 lb w/ .17 in. additional deflection. first deflection could be doubled, second deflection is
6. 20 years - contant static load ~ 30000 lb ±20% maybe 500,000 cycles.
7. see above, aloowed relaxation - no requirement - let's say 1 inch.
8. Ambient
9. Commercial
10. None
11. Spring is part of a support system for a 1/2 million pound, tall vertically mounted cylindrical shipboard structure w/ vertical 3/4g loads. The purpose of the system is to limit flexural loads at the base due to small shear movement of upper lateral supports. So, loads are compressive, although I suppose arrangements can be designed to use tension or torsion. Probably 2 inch under static load is max. About 40 springs would support base flange of cylinder.
Again, I'm looking for a supplier that works w/ this size spring. Have considered air springs, but I think they would have to be pretty large diameter unless they operate at high pressure. Also considering rubber mounts.