Sorry for the delay on answering again, I was at work when I replied to you last time.
I'm glad I helped with that other one. About the other questions:
1): Yes, there is currently a bug where anything that inflicts Slowness 3 on the player might make it stay forever on your characte (such as Slowess 3 from tempests or from eating Gummies). The way to counter this is by simply leaving your world and logging on it again. If it doesn't work, close all your Java applications (via Task Manager) and re-open minecraft.
2): I would like those screenshots, I will send 'em to Brandon (Kingbdogz) to see what he can do about it. I will also add to the Icestone wiki page :D
3): I have messed around with Quicksoil and Quicksoil to answer your question and, Yes, there is a way to slow down yourself.
1st, you use can Soulsand (from Vanilla Minecraft): It takes 9-12 soulsand blocks to fully slow you down or it takes 7-9 blocks if you add Ice (from Vanilla Minecraft)beneath the soulsand.
2nd, you can add a 1-block wall of any block in front of you, or 2-block of Cold Aerclouds (A way to keep moving doing this is to add a ladder to the block; you will then switch to climbing speed when you touch the ladder)
3rd, you can make a small stair with 2 stair blocks higher than the level of the quicksand to slow you down almost completely... you will keep walking forward, but now normal walking speed.
4th, you can use a piston-based "stop" with two methods: or you add a clock that constantly turns on/off the pistons (you will then stop whenever the piston is "on" because you will hit it) Or you can add a tripwire hook half-way through where you are going to so the pistons will activate whenever you reach that place
5th, and the best way: If you have an awesome timming, you can add a minecart at the place you want stop and then click on it as soon as you reach enough range to do so. As you will instantly go inside the minecart all speed will be lost
I can't think of any other way to counter this effect, sorry =/ Hope I have helped you with enough information!