1. Yes, you'll get stroker domes cut. The pistons will travel up into the head 2mm. A LOT of people do this.
2. As answered, yes, standard run of the mill Oring kit for the pro design or noss head will work.
3. Yes and no. Since you mentioned a dune port, my advice would be get a set of 33 or 35PWKs. They will give you more mid and top end than stockers. They are NOT critical, but they would enhance the motor package overall. Same thing could be said for the pipes. They are great trail pipes...but a set of CPIs would be better down the road.
4. You must get the cylinders ported to match the stroker crank's added stroke to make it worth it. You MUST tell whomever is porting them you plan on running cut domes and not a spacer plate. That is important.
Ok...it's not that you 100% HAVE to get it ported to run with the stroker crank, it's just that if you're gonna spend the money on the crank, make sure you get it ported to match the crank.
Get the long rod stroker crank, and make sure you get the correct 795 series pistons to compliment them.