That is a pretty wide open question. I assume you are wanting to place Electrical Equipment, so first goto an electrical view. Use your View Template to make sure it is setup correctly with the Visibility Graphics. Next, is it a 'free floating' piece of equipment or a "face based" object? If free-floating (like a transformer), you should then be able to place it easily, with only checking the elevation value in the properties to insure it is visible. If it is face-based (like a panel), then it will default to a vertical plane, but you can change it to other face angles with the toolbar buttons (should be up at the top-right side).
Depends on many things including - version of RME and content pack, are you using OOTB families, are you using linked files for your architecture and structure, type of electrical family being inserted, etc.
If OOTB families then they are element hosted families and won't host to walls etc. in linked models.
You need to be a little more explanatory in your question
Try looking into the tutorials or perhaps referencing some of the learning aids as mentioned throughout the forum, the most recent post being Manuals or Help Guide Books. I recall that you were looking for this information in previous posts. Were any of the suggestions then helpful at all?
Do you mean in Revit or Rivit? Revit is a CAD program, rivit is what a frog does. I use my mouse to pick first the type of equipment and then use my mouse to further my selection in the Properties palette. Then I place the equipment with my mouse onto the floor plan of the view that I have setup. Then I may select the equipment with my mouse and further refine the elevation placement by picking with my mouse in the Properties onto the elevation value, or possibly the Offset value, depending on the equipment. Perhaps a training class should be pursued in your future, or at least do some online tutorials or buy a training manual.