Wooden worktop and upstand. So many questions....

[Claydon Lad]

Hi buster, and welcome to the forum.

1 - you usually get a metal strip with the appliance, but just use a few wide strips of foil tape on the under side.
2 - if you get the tops at 650mm wide, - there's plenty out there, you can bring the units off the wall so it gives you more width. Personally I think it looks better with the upstands going all the way across.
3 - butt join, run the router along the two edges first so you get a good one. Take the sharpe edges off either with a chamfer or small round over bit. Bolt up as laminate, lots of debate on here how you  glue the joint up. We've used wood glue, never had any issues.
4 - you can get tops 4mtrs long .... www.woodworktops.com for one.