Alchemy Fortify Magic School effects are different from enchanting. The don't reduce the spell cost and instead raise the magnitude (Destruction, Restoration, Illusion) or duration (Alteration, Conjuration) of spells.

I've tested it and the third word of DA and the perk each multiply the duration by 1.5. Here's the breakdown;

1 word does 8 seconds normally, 12 with stability, and 16 with DA & stability.

2 words do 12 seconds normally, 18 with stability, and 24 with DA & stability.

3 words do 16 seconds normally, 24 with stability, and 36 with DA & stability

Remember, DA will only affect duration if slow time is used while under the effects of all three words.

It's a shame. Bethesda at their best giving us an ability to grow plants and release a bunch of useful ingredients that you can't plant 

Oh, wait.  I can confirm you can go into the cave without being on the correct part of the quest.  Just realized I just did this for my story.  The gate isn't enabled when you go in without the quest being active.  In the center, you'll also find the scraper and activator for the tree are also disabled.

So, yes, you can go into Ancestor Glade anytime you like.

Great info Kyrie! You should've added "Spoiler warning to The Longest Road – Ch. 8 – 1: Jode's Wrath"  Now I'm even more intrigued!

No, it's not a spoiler.  I haven't even written that part yet, and I figure no one will know exactly what I'm talking about. ^^

another great build, your getting really good at this Adrik

Haha, I just got back from checking as well!  So three's a crowd.  Definitely possible to get the flowers before Unseen Visions.

Lol.  I know.  I'm just so cruel like that.  I'd say it was good that you at least got some exercise (like I do when that happens to me in real life), but you actually didn't.