Need help for a Buckwheat Beer

So I have a friend who is absolutely obsessed with brewing a buckwheat beer but he hasn't brewed beer in years. So I offered to help. I've been doing some reading and from what I gather there aren't a lot of beers that have the bulk of their grain be buckwheat. He really wants a buckwheat heavy beer. i believe the beer is meant to be GF so I was going to make up the rest of the fermentable with rice extract, roasted Millet, and possibly molasses (for a little color). So questions that I have are:

The use of amylase enzymes to help along the process in the mash are said to leave a lot of unfermentable sugars. How noticable is the sweetness in the overall taste?

Would a darker beer be more forgiving?

Should I even use amylase enzyme?

This would be a partial mash.

Tentative recipe:

5# Buckwheat
4# rice extract
1# roasted Millet
8oz Molasses
.2oz Amylase
2oz Centennial @ 60
2oz Cascade @ 30
1oz Cascade @ 5

Would this work for 5gal batch?

Never used it, but unless it is malted you would need to add amylase to convert the starches into sugars. If the buckwheat is flaked you can mash as is, if it isn't you'll have to boil it first to gelatinize the starches. Some rice hulls will help with lautering, probably a good idea.

If you want to keep it gluten free you should use a dry strain, liquid yeast are packaged in wort.

That is a lot of hop bitterness, although maybe that is what you are going for.

Hope that helps, maybe someone with some more practical knowledge will give you some feedback.

Some changes to the buckwheat recipe and i'm now in the midst of the malting process. I have the buckwheat in the basement hoping it'll sprout in a couple of days. then it's off to the drying and roasting. I still have to do another 4# but I wanted to test drive the process. I will say that the instructions I've read so far have been vague, with a few that were really helpful, but hadn't dealt with buckwheat, so I was still at a loss about specifics and so I've been taking lots of notes for future brewing.