hi, gusto ko sana palitan yung stock speakers ko (rear right is already on its way out na, basag na ang tunog)

car: 2009 Toyota Corolla Altis 1.8V
factory speakers: 2 Tweeters, 2 front speakers (6 inches yata), and 2 rear speakers (6x9 yata)
headunit: Pioneer AVH-4450BT 2DIN

what can you suggest mga sirs?

mga requirements:
1. below 15k only
2. as much as possible stock look only (no protruding speaker covers, no mounted tweeters over the dashboard, must use all space allocated for the stock speakers especially the tweeters)
3. sa 6x9 po ba, ano yung three-way, two-way at one-way? for this setup, what can you recommend?
4. no amplifiers for the mean time pero gusto ko ready for amplifier na when time and money permits
5. shop that is an expert in installation for this (within NCR lang sana)
6. no in-trunk subwoofers (but is it ok kung under-seat subwoofer ang gamitin ko?, I can't compromise storage space kasi )
7. for general music lang, I just want something more clearer and merong "dating" compared to the stock speakers

questions:
1. do I still need to upgrade the wirings kahit hindi wala pa akong amplifier?
2. is it ok ba na gumamit ng higher wattage speakers kahit hindi ako gumamit ng amplifier? maapektuhan ba yung sound output like mahina yung sound?


any help would be greatly appreciated mga bossing.