I have a 2000 accord v6 my question is can i replace my 4 speed automatic transmission with a 6 speed automatic transmission from another accord?

 

You can, but it'll be more work. I only say that, as you'll need the ECU from the 6 speed AT car, along with the wiring harness. The newer cars got more electronics involved in the transmission. As it is, your 2000 uses a 2000 to 2002 trans due to having some added electronics over the 98-99 version that look like your own (mid year split).
You'd be better off trying to find a 2000 to 2002 V6 AT trans and installing it (then it's just a mechanical swap, and all of your existing stuff stays).

 

Can i swap the intake from a j30a4 for a j30a5 ? it's still the same motor 3.0

 

No idea, as I'm not really into the V6 cars. All of mine are 4 cylinder cars.

 

I rather doubt an intake swap will get you much; if you want a bump in power from our current engine you're probably going to need to swap out the heads. I'm thinking it would still be better, faster, cheaper to simply drop in a complete J35.