Lots of questions, lots of suggestions. First off, what kind of speakers do you currently have? Second, what is your overall budget?
About the speakers and subs you posted links to...
Those are really both for use in car applications. Not only that, but they're going to have CRAP for sound quality.
All subwoofers need an enclosure. What type you like is up to you, but either sealed or ported works best, NOT bandpass. You can build your own subwoofer if you want using a kit from
Parts Express. That's probably about the best deal you're going to find for a subwoofer.
The amp you have, well, I would also venture to say is quite lacking in ALL areas. If you're serious about getting good sound, you're going to have to invest a little money. I assume this is a music/movie system, so a good sub is important. While the sub I posted won't dig all the way down into subsonic sounds, it's a good start.
A preamp is a device that takes low-level inputs from different components (like CD players), routes the signals as you choose, and then steps up the voltage for output to an amplifier. An integrated amplifier is a Stereo Preamplifier and stereo amplifier in one chassis. A reciever (unless stereo) is a multi-channel preamp (as in surround sound) that usually offers video switching and a multi-channel amplifier in one chassis. Recievers many times have Equalization and other forms of sound processing to improve the sound in your room.
When you say VHF, do you mean a picture like the first one attached? If so, you have an older TV. It won't really let you take advantage of all the quality of a DVD.
Unless your room is very small, I would look into a 5.1 surround setup for movie watching (if you watch them a lot). There are many possibilities out there for a 5.1 setup, which i will elaborate on if you want. But first, I need to know what you own right now.
As for the items listed on e-bay, I can say without reservation that they are basically crap. No offense to you, but it's the truth. Before you make more purchases, spend some time here and get a better idea of what you need to be looking for.
