Yes you can run a network cable directly from the access point or router to the computer that you will be using them with.

The antennas are removable. If you can use an indoor antenna the "pringle" can might work for you. They can be purchased at the link below.  I'm using one of these at my daughters house.  You can make it cheaper but probably not any better.

http://wirelessgardenstore.com/SearchResult.aspx?CategoryID=28

I purchased my antennas and cable from SharperConcepts.com.  Prices and quality are both good for consumer products.  Remember the longer the cable the more loss in transmit power you will get.  So you need to keep the cables as short as possible. http://sharperconcepts.zoovy.com/category/24ghzantennas/

 YSC-HG2412P  is the model number of directional antenna that I ordered. Its making a 1/2 mile trip to the router just fine.  It even is going through some trees.  YSC-HG2412U is the model number of the omnidirectional antenna that I used at the base router. I used 20' of 400 Series Cable Assembly to go from the router or AP to the antennas.  Its about as big as your thumb.  Kind of hard to run but has low signal loss. Radio to Connector Type Cross-Reference is available to help with the type of antenna connector on your radios http://sharperconcepts.zoovy.com/category/connectors1/.

Yes there is a million ways to get your network up and running stable.  A lot of different antennas and radios.  Our network has been more reliable than I ever thought it would be.  Its been up for 1.5 years with very few problems. If you aren't very familiar with networking do a lot of reading.  After you read enough it starts to make a little since.  A couple of good sites to check out are:

http://www.thibor.co.uk/

http://www.linksysinfo.org