Shower Drain?

I need to know how I should hook up my washer for drainage in a first floor laundry room I am building. I will be using 1 1/2" pvc to the vent stack. Right now the washer drain is in the basement with the drain hose just sitting in the soil stack (talk about messy). Where should I place the trap, above the floor in the laundry room, or below the floor in the basement? Another question I have is this: Will it be OK to have the drain pipe from the washer just resting inside a drain pipe going to the stack or does it need to be connected somehow so that it is sealed?

Thinking of replacing my current bathtub, a plastic or fiberglass unit, installed when the house was built 12 years ago. Want a bigger and deeper tub. The drain and vent are on the side in the middle of the length of the tub, The spout is at one end but actually comes out the wall above the tub so water supply doesn't seem to be and issue. We have a separate shower, so no diverter. There is a tile surround on two sides, the end with the water supply and the outside wall that the tub butts against where the drain/vent are. At the other end is a tiled shelf which could be removed/modified to allow for the larger tub. I've seen TV shows which demo installation where they pour a cement /mastic compound down to have the tub bottom seat to that. This is a Florida house on a slab, no basement or crawl space. Not planning on saving the tub, just want to make sure I don't have to rip up the slab to install the new drain. Trying to see how tough it will be to match the old drain with a new tub (are these standard?)and whether removal will be in one piece or ripped out in sections.:rolleyes: