With 100 alchemy and a set of 40ish% gear, I can make a 30% for 30 seconds Fortify Enchanting potion.

1. When using the enchanting table (xbox 360), will that 30 seconds keep counting down while I rename the item being enchanted or is it suspended while I'm in the "keyboard"?

2. Is it possible to get longer duration potions made? I know the commercial ones are up to 60 seconds, but I haven't seen one above 25%. I think I have all the relevant perks, there doesn't seem to be any others that might extend the duration. Is 30 seconds "normal"?

Time stops when you go to name the item. You should probably plan on one item per potion. Maybe you can get two if you are very quick. I have alchemy and enchanting maxed and vampire/necromage and the best potions I can make are +38% for 30 seconds.

Another trick is to use the "slow time" shout right before you chug your potion. That lets you click into the enchanting table and get stuff set up without using up much of the potions duration. As soon as you actually enchant something, the shout's effect is turned up, but at that point you've used maybe 3 seconds of the potions duration, and can likely crank out enchantment or two.