re: Homebrewing: All Grain Mash Tun

So, got home, had a couple beers, and watched some video's on youtube on brewing all-grain.

I watched one video from a Virginia Tech guy (about 30 minutes long) that was very good at explaining.

So here is the technique from what i gather.

1. Heat water up to 170 (depending on your recipe). Pour water into your mash tun (in this case 10 gallon round cooler). Put on lid, let the cooler heat up a bit, then drain back into the pot. Add some 5.2 ph stabilizer.
2. Add grains to mash tun (doughing in). Pour water in slowly, stirring constantly to avoid clumps. Once added, your temp should be about 154 degrees. Let sit for an hour.
3. While sitting, heat up some sparge water (about 3 gallons depending on your recipe).
4. Drain mash tun slowly into a pitcher, and keep recirculating into your mash tun until your wort extract is clear. (has a german name for the process, i forgot what it is). Be careful when pouring back to not disturb grain bed.
5. Once your extract is clear, drain into brewpot very slowly. Once the water gets down to the top of the grain bed, add sparge water (should take about 30 minutes to an hour).
6. Once complete, measure your pre boil gravity. Then brew as normal.

I bolded the sections i have questions on.

1) Is the PH stabilizer necessary? or is this mainly for "bad" water? Do yall use it?
2) All the videos i've seen, show adding water to your mash tun first, then adding the grains. However, in how to brew, and complete joy, they say to add the grain first. Does it matter?
3) What temps should the sparge water be? below 170?
4) All of the videos i've seen, either a manifold or SS filter was used. What are the benefits of a false bottom over the other 2 options? Better grain bed stability?

ETA: Also, how much sparge water is typically needed? I have a 5 gallon old brewpot, and would rather use that, than buy a new one if i don't have to.