Fresh Blackberries - how to prepare for beer

My son in the Air Force said he though a beer with blackberries would be cool since this is the season for them - so I decided to make him a batch to take back to base with him. I decided on a sweet brown ale with an ABV around 4% for the base and picked up the blackberries today. I won't be brewing for about a month, so I will freeze them. A couple of questions -

1 - do I need to blanch the blackberries prior to freezing? If so - how is the best method?

2 - when is the best time to add blackberries (or any fresh fruit) - in the end of the boil or into the fermenter? Also - I ASSume you would crush them prior to adding - right?

3 - any additional tips to get the most flavor transferred to the beer would be greatly appreciated. I don't see my boy often, so I want to get this right the first time.

Thanks guys,
Dan

I'm doing a blackberry Hefe. I'm going to do a vodka infusion and add it at bottling but you can put them in secondary too.

This is what I did with strawberries. Imagine it would be the same for blackberries. Key is don't boil, and might need to add pectin if you are looking for a clear beer.

https://www.homebrewtalk.com/f39/adding-strawberries-2ndary-106243/