1. how will the specs of the hard disk (i.e. 5400 rpm v. 7200 rpm, diff types of SATA) matter sa performance at SQ ng laptop audio setup?
There should not be much difference, as long as it's not a very old model. A large HDD will obviously help in terms of data storage. The only time you'd need a fast HDD for this application is if you plan on multitasking disk-intensive tasks. A fast HDD will make the computer more responsive, but it will not make it play music any better. Some argue that it actually detriments output quality because of the greater transient power demands (from the stronger actuator often needed to position the head fast enough).
2. will the amount of memory (2Gig vs 4Gig) matter?
This depends on your player, the files that you play and how much background tasks you're running. Typical players should be okay with 2GB RAM with typical 2-channel file types if you manage your OS and background tasks properly (even 1GB could work as a bare setup). 4GB would be a more comfortable spec in most cases, and is a sensible option if you're buying new (since RAM is cheap). Though not popular, memory-based players consume a lot of RAM when playing back high resolution files, and may be better off with 8GB or more.
3. ano sa specs ng processor (i.e. speed, # or cores, latency, etc) ang kailangan tignan para maganda ang performance at SQ ng laptop audio setup?
You don't need much processing muscle to handle just audio, but it helps when multitasking. A faster processor may be desirable if you plan to use the notebook for more demanding tasks (multi-purpose computer). For a dedicated setup, any recent entry level notebook processor (Intel Celeron or AMD Fusion A4) can comfortably handle high resolution audio formats.
Some purists actually prefer moderate power processors on the same platform because the lower load on the same power supply causes less ripple. There are people who go out of their way to under-volt components to reduce power demands, then disable power and clock gating features to make the draw fairly consistent. After which, they swap the power supply with higher spec and lower ripple replacements. I have gone this route in the past, and the gains are often too little that most people should not lose sleep over it.
Two cores in a processor is normally enough, granted that the cores are fast enough. This lets you manage affinity (if you're OC with latency) to let one core handle your application's processes and the other your background tasks and services. Again, the latter tweak is truly optional as windows can handle processes and services quite efficiently without user intervention.
Factors to consider when selecting a computer for audio:
1. Other intended uses
2. Playback formats to be used
3. Interface sensitivity to latency
4. Intended buffer depth
5. Software to use
6. Overall system cost
7. Expected lifespan
8. Power consumption
9. Individual preference
Though these things may look daunting to some, the level of complexity really varies per individual. It can be very simple or very complex depending on how you want it.