Yes, In fact unless you are a mouse there would be no other way. You do have to climb under the car an take out the two bolts in the bracket that support the manifold.
Remove carburator then intake manifold then cylinder heads
no it is not possible
Yes they are the same, but there not on the sides of the engine. There are 2 of them and they are under the intake manifold. You will have to remove the intake to get to them.
It is inside the upper intake manifold. It is attached to the fuel injector poppets with a bracket. To inspect/replace you must remove the upper intake manifold.
In the cylinder heads.
by hand :)
No. Not without switching the cylinder heads. I think it was 89, Chevy came out with the 1st generation Vortec heads, which require a different intake.
the fireing order is on the intake
under the intake plenum behind and attached to the spider
They are under the intake manifold.
Remove the intake manifold retaining bolts from your 1996 Chevy Astro Van. Remove the manifold gasket and clean the surface. Reverse the process to install the new intake manifold gasket.
It should be printed on your intake manifold.