newbie: some questions

I've done some reading on the web about wireless networking but there are
things that i need clarity on:

1. Does an access point perform the same operations as a wireless PCI card
---> Where if i wanted to setup 2 pc's on a peer-to-peer network where
my pc had an access point and the other PC (600m away)
had a wireless card would that setup work.(this is just the
initial setup for testing 5 more people will be joining if i get everything
going
If i do get this going i would setup a domain controller
(domain1)
---> Then i would be able to run a cable from the access point into a
normal ethernet card using cat 4.5 and RJ45 jack

2. In 2 months time i will be connecting to another network 3 miles away
that would also have a central access point that would be a file and
internet server.
---> Would i (with an access point be able to connect to that network).

3. The setup would be
---> My access point with people in my network connecting to my domain
(domain1)
---> What hardware would i need to purchase to connect to domain2 (3
miles away -- Line of Site no obstructions)

The reason i want to have an access point at my place is because i have the
highest point with line of sight and no obstructions of all the people that
will be connecting to (domain1).

Any help and suggestions would me very much appreciated because i am really
new to all of this.Thanks.