1. You definitely can swap out the mag and bolt releases. They say so in the video - all parts are interchangeable with all ages of 10/22s.
2. You can't compare the price of this to a VQ hammer kit or Kidd trigger job kit. This is a complete group. At a street price of $70, it's a little over 1/3 of the current $200 sale price of the Kidd full single-stage group. I am confident that it isn't as nice as the Kidd, but the gap of $130 is serious money. If you had an 80% receiver and needed a trigger group to complete your build, this might be a good solution. Takeoff OEM groups seem to go for $50 and more on fleabay, and then you have to buy the upgrade parts.
3. Some people buy high-end MBs and BMWs because they want refined aesthetics with their performance. Others buy WRXs because they want performance at a price. Same with the 10/22. Not everyone wants to spend the price of an entire 10/22 on the trigger group. Some guys with expensive tastes and fat wallets buy only Kidd. Others want better than OEM, but are on a smaller budget and don't believe that the aluminum trigger housing improves their groups on the target. I think there will be a good market for this product - if the product proves to be good.