1. When you glamor something to your body (Example: Glamor a level 43 weapon to a level 50 Dragoon), is it then easier to spiritbond the level 43 weapon?
> I don't think glamour affects the rate. If you want something to spiritbond faster than usual, meld a cheap grade 1 materia into the item that you want to spiritbond. Each meld if I'm not wrong boost the speed by 20%, it's advisable to only meld materia into the safe slots as overmeld is a waste of gil should it fail.

2. Do FC Commands and Spiritbond Potion's effects stack?
I'm sure they do, I've seen many people use the potion and activate the buff and wear two Meteor Survivor rings at the same time. That should give the user Increase Spiritbond rate + 12.

3. How do you spiritbond?
Normally people will do the following.
> Purchase gears from NPC, ones that has ilvl45 and above. Wear them all and preferably equip your best weapon, get as many spiritbond increase stack (Meteor Ring, Spiritbond potion, etc) and form the "Red Smock Gang" party at Urth's Gift where it has the level 50 Water Sprites at the end of the map. Start destroying each one of them until the environmentalist filed a report on you.
There are other ways to do this fast but the one mentioned above is usually the common method. For higher ilvl gears like 70 or 90 they are usually spiritbonded inside dungeons.

Hope this helps.