Alaska sells a powervent kit that includes the 6" by 4" adapter. So does LL, their kit is more complete and includes a rheostat to control the draft, but they are only UL listed for use with LL stoves. You will need a barometric damper, WMO-1 safety switch, rheostat and adpater. Talk with your Alaska dealer to see what he (or she) offers.
You should repost your questions in a new post in "venting, plumbing..." and there are plenty of folks who can give advice and help you with the setup and running of your stove.
Once you install your PV you can borrow a manometer to verify your settings, however I would not recommend running a power vent without running a manometer to monitor draft. If you want to get on the loaner list simple PM me with your address and phone number and you will be on the top of the list for the next one available.