I'll answer the spreadsheet questions first. FoK question is interesting too, but my gut feeling is if you want a spec to maximize FOK damage, you may not even need to go down to 51 in combat, perhaps a 40/31 mix of assassination and combat would work better for FOK alone (
40/31/0)
Sp00n: I noticed low sensitivity of DPS values to number of combo points of SND in the past for HaT specs. The reason is when you select 1 in combo point restriction field, it is only a lower bound, it says use SND if you have at least 1 combo point. In reality with 2 combo points per second income you are most likely doing 3+ SND's. You can check it in the Combat tab. As far as GCD capping, I don't think with 2 crit/second you are GCD capped, you have to wait for combo points and balance your energy, so you not spamming eviscerate on every GCD. (Although if you set minimum eviscerate combo points to 1 or 2, you will probably start spamming, but then you will quickly run out of energy because of reduced reletless strikes procs).
Pepperry: You are having a weird problem that as far as I know noone else observes. My best guess is you did not change trinkets properly. If you simply select 1 next to one trinket, hit delete (clear contents) that one. Then put a 1 next to grim toll, everything should be working fine. #REF problems appear when you actually delete a cell as opposed to clearing contents. So since I cannot see what you did to your version of the spreadsheet, it's best that you redownload it and try again. Let me know in a PM if you continue having this problem after you redownload the spreadsheet.
Shadowrom: You are probably using an older version. Use 3.1g, and make sure you load proper mutilate DPS Strat settings.
P.S. the file does not work in Open Office because it does not support VBA, I will add this comment in the main post. Since I do not have much experience with OO, I cannot even tell you if it's feasible to create a working OO version of this simulation.