I believe if you are a renter, you may have to have written consent from your landlord for the install.
Standard install is to find an appropriate site for the dish, ground the dish, run cable along the outside of the dwelling to the room where the receiver is located and drill a hole in the wall there.
Sorry, but the dish must be securely mounted or you'll have a devil of a time getting signal when you need it. You may be able to hide the receiver, that is if you are sure you know how to reattach it.
Appointments are usually in a 4 hour block 8am to noon or 1 to 5pm, exact time cannot be guaranteed.
I'm not sure about Dish-on-line but I think there is a reserved partition on the drive for this so it does not impact recording time.
The sling adapter is not for receiving downloads, it is for sending your live TV or recordings to another device.
I believe dish-on-line and sling are two seperate entities that are not related at all.
No TV, so you will watch on a computer monitor? Then your picture quality will be totally dependent on what type of inputs your monitor has. If you're lucky it may have an DVI or even an HDMI input, that would be fixed with the proper cable, but if your monitor is VGA input only, you will have to get the video signal into your computer somehow and HDMI and component input solutions for computers will probably run you around $200 (the price of a small HDTV). Other than that you will need atuner card for your computer, but be sure it is both ATSC and NTSC, because the RF out from the Dish receiver is NTSC.
Fees, well, if you get a DVR there is the $6/month DVR service fee. If you have only one receiver, that receiver fee is included in the basic package price. From there the second receiver would be charged a fee, but I don't think that is in your plans.
I think that is all, I'm sure if I'm in error, somebody will be more than willing to point it out.