Okay, this is what you do.

1. Know your budget
Truthfully, this is ironic of me since I technically work on an open-budget basis. But then again, not everybody is as passionate as me when it comes to car audio (my modifications alone is in the realm of 6-digits after all). I will advice people who are beginning their project to have a budget. Because the budget will dictate everything. From your choice of gears, installation, and even installer choice. You'll eventually have to compromise one way or the other so that the components will all fit "within" the budget.

I'll give a sound warning: 90% of people I know who has a budget of 50,000php upwards will overspend their initial budget.

2. Find an installer and state your budget.
Most installers are two things combined: artists and entrepreneurs. Artists is because the ideal setup is one that's a blank slate. In that point, a lot of them disdain continuing the work of other artists. So choose wisely on who you want as an installer. Talk to them and judge them on their customer service, their knowledge, and experience. Entrepreneur - because this is a business. Some installers will push you products which have a higher profit margin for them regardless of their performance. Now, each of these artists are experienced and will have differing philosophies on how to construct your project so don't expect Installer A to push for the same products as Installer B.

3. Research and Listen
This is where most of your time will be spent. Think of this as constructing a blueprint for your house. First thing you do is research - there's a wealth of knowledge in backreading KAC's threads. Tsikot's very own "audio setup for beginners" thread also has a huge backlog of posts (mostly by me) which may come in handy for your questions.

After researching, start listening. Now, how to listen. First is contacting your installer - usually meron yan on-going project or an already finished project. Ask permission if you may "audition" the setup and just listen. Listen to a lot of car and you'll get a rough idea on what you'll like - which will probably make you change your initial equipment to suit your wants.

And before you finish reading my post, I'll remind you to pick your route: SQ, Loud and Clear, or SPL. These are three distinct routes and it's one-route-per-system. I will advice you not to try an jack-of-all-trades system as most I've seen who attempt only ends up disappointed.

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As for replies...

Rear Speakers
You won't need them. Your front speakers is loud enough so that you won't ever need your rears.
Case to point: I've never heard anybody complaining inside my car why it doesn't have rear speakers.

Dynaquest amplifiers
SRP of Dynaquest amplifiers are around Php16,000 if memory serves right. Will I recommend it? I won't because there's usually better ones out there. The Dynaquest amplifier is a hybrid tube amplifier. The tube is at the pre-amp stage while a solid-state MOSFET is at the power stage. Truthfully, you won't really hear any "tube-ness" in the sound with hybrids. This is because most of their bias is set too low to affect the music. So it's either you go for pure tube (not recommended in a car) or you go solid-state (what 99% of us use).

Also, I haven't seen one being purchased first-hand for a long time na. They were popular back in 2008-2010 but since have waned in popularity.