Does your computer get its IP address from your service provider or a router, or do you set it to a known value all the time?
If you use DHCP (getting the IP from your ISP or a router), then you'll need to install a DHCP client. I believe the BLFS book goes into that, but I haven't done it myself. When you use DHCP, everything should be automatically configured when your computer gets its IP address.
If you use a static IP (one you set manually), then you'll need to edit your /etc/resolv.conf file. You can read about it with
man resolv.conf, but here's the short, short version. You need a line for each DNS server you use, and each line would look like:
nameserver AAA.BBB.CCC.DDD
nameserver EEE.FFF.GGG.HHH
Where you obviously replace the capital letters above with the right IP addresses. If you don't know them, then your ISP should be happy to give them to you. You usually have two: primary and secondary DNS server. Those changes will get you access to the Internet.
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To avoid IP address conflicts in your local network, then you simply have to change the IP address in the network configuration file you created in the LFS book: /etc/sysconfig/network-devices/ifconfig.eth0
Change the IP address line so that the last number in the sequence is different from the other machines on your network. If using DHCP, then this should be taken care of automatically.
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You may be familiar with this already, but just to be thorough, you can avoid typing IP addresses if you put information in your /etc/hosts. So, if you have another computer on your network named rimo_main and an IP address of 192.168.0.15, add this to /etc/hosts
192.168.0.15 rimo_main
From that point on, you can type things like "ping rimo_main" and your computer will know to use 192.168.0.15 when it sees rimo_main.
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For networking Windows and Linux Boxes together, you'll need
Samba. There are LOTS of documents describing how to create Linux shares visible from Windows and vice-versa. It's a very common thing to do, and I've seen many threads about Samba in the General/Software forums in the past, and each one was answered. So there's a lot of help available should you get stuck with just the dry documentation.
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Now, your question about "picture repetition frequency"... I assume you mean either horizontal or vertical refresh rates, right? As opposed to something like a background image changing in KDE? For the horizontal and vertical refresh rates, you'll have to modify your XF86Config-4 file again. This time, I believe you'll be messing with the "Monitor" section. I don't know what the options are off-hand. I'll have to go home and look it up. If you need to know ASAP, then the man pages should be able to tell you how to specify them, but there is quite a bit of information that you'll have to sift through to find what you need.
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man fstab 
That will tell you everything about the format of the file.
