The top cover is pretty straight forward, remove the bolts and nuts around the edge, and pry it up. If it still has the original Oliver gasket sealant, they can be tough to remove. That stuff held really well.  From there, remove the old gasket, replace the o-rings (should be 12 of them plus possibly a couple of small ones near the front) put on a new gasket and set the cover back on. The biggest mistake I see happen is not paying attention to the position of the hydraulic levers when the cover is set back on. The spools that they engage are in the cover, so the levers have to be held in the neutral position to line up properly. If they move really far ahead or not much at all once the cover is on, then something missed its spot. Lift the cover up just a little and try again. Make sure the levers are properly lined up before bolting the cover down.

The pipe coming up in the front is just a reservoir port. Normally there is a plug that screws directly into the housing to cap this port off. You can remove the pipe sticking up on yours and replace it with a cap, but it would be a good idea to pump down the reservoir before you do it so you don't end up with an oily mess.