my first question is about your network do you have a wireless router on that network? if not then what ever you use would have to have a wired connection to your dsl. If you put in a wireless router to your network then yes you could sit probably anywhere in your house and use it. It is just another type of computer so would be used as such really.
A kindle uses it's own wireless which is built in and there is no charge for using it, it comes as part of your kindle, it is what allows you to download books directly from the kindle store to your kindle. You would of course have to be in an area where the kindles wireless could gain access, some very remote areas might not have good access. Once you have books on your kindle if you set up a kindle for pc on your computers then you can simply choose to sync it to your kindle device and it will send all of your kindle books to the kindle for pc, you will have them on both devices, you are allowed to have several kindle for pc programs and they are totally free so if you want it on your pc and an ipad you could however I do not believe it supports apple products yet, I know it is in the works. I don't know much about the ipad it self they are pretty new yet.
whether you could watch tv or movies really would depend on the speed of your connection. It is possible but may not be a good option for a slow connection.

Thank you, Ravencajun, for your response and information. I do have a D- Link router model WBR-1310. It was installed for me and I have zero understanding of how it works or how to utilize all its features. All I know is I can use my laptop anywhere in the house. I would not consider buying an IPad until it has been out for a while and there is more information about it available. I do think it would be more comfortable for reading books but it is not as small and portable as the Kindle.
Regarding the speed needed to view video, I am not able to watch most You Tube videos or episodes of TV programs without waiting for the streaming to catch up. My DSL provider says I have an excellent connection and I know so little about my computer that I don't even know what questions to ask to fix the problem. I really need to find a good local computer guru who can come to my house and trouble shoot. I am almost 66 and computers don't come easily to me, but I do want to enjoy all the features that are available. One of the screen names I use is Computerdyslexic and it is really suitable. After I get my income tax refund I will ask the local community college computer instructor to recommend a gifted and patient student to tutor me for a few lessons. I can learn, but it comes slowly and only after a few repeated lessons.

the lessons from a student would be a great idea. I am in the senior category too and definitely have to keep on my toes to try to keep up these days. I do it to try to keep my brain cells functioning rather than allowing them to sleep LOL
Unfortunately just because the DSL provider says your connection is good does not always mean it is, many things can affect dsl, including the lines to the house and even in the house and how far you are from the closest CO station.
I do not have a kindle, several in my family do and I have used theirs, I do have the kindle for pc on my netbook and all of my computers and enjoy it. They have come out this year with a larger size kindle which would be my choice if I got one since I have such bad eyesight. I use my netbook to read my kindle books on and it works pretty well especially since the kindle for pc is free.
So far they have not made a kindle format for mac or apple so you would have to wait for that to be able to use it on the ipad.
They make 2 ipad versions one that is wifi and one that is wifi with 3G, the 3G you can use with cellphone or an aircard from a cellphone provider. Both use regular wireless wifi so would work with your wireless router connection.