Cool beans. A Cebu raven. No wonder you write better English than the average Tagalog.
Anyway for now, I'll let this thread stay in game help. But as we shift the discussion more towards just your AC design, I'll move this to LR designs.
For starters, you can take a peak at this (huge) thread for a previous new player:
http://ravenrepublic.net/forums/showthread.php?tid=1978
It's quite a read but it'll most likely answer many of your questions.
So onto your AC. I see that you like low-drain light-midweight bipeds. That's perfectly fine. And most AC players tend to prefer that AC class.
Anyway, onto appraising your parts again:
Head: YH12-MAYFLY --> (nothing particularly good about this head. The S2 you were using before was better. But like I said, pair it with the 69RA starter radar)
Core: C9BE2 --> So-so as an Exceed-Orbit core. But there aren't many alternatives. A standard hanger core like 98UL or U2 is usually better. But I guess it pairs nicely with your PIXIE3 here.
Arms: MACAQUE --> great arm. One of the best in its class.
Legs: DINGO2 --> heavy lightweight / light midweight. Low drain. It's no wonder you were drawn to this leg. Really good set, but don't let it restrict your growth. It has a tendency to do that.
Booster: VULTURE2 --> excellent. But it pairs better with the G91 generator UNLESS you're using an OB core.
FCS: MF03-VOLUTE2 --> decent FCS for standard-type weapons but doesn't really go well with your PIXIE3. F73H (SW) is probably your best bet, considering both your P3 and missiles. COWRY (WS) will give you the biggest lockbox but will limit the range of your missiles.
Generator: G01-LOTUS --> nothing really wrong with this. But G91 will give you more energy faster
Radiator: ANANDA
Inside: NONE
Extension: CR-E92RM3 --> best missile extensions in the game.
Weapons:
Nymphe is nice. But usually, it's paired with missile-specialized FCS like MONJU so that you can maximize the number of locks.
PIXIE3 is a great machine gun. But your previous R2 is probably more versatile and easier to use.
Optionals: O01-ANIMO, CR-O69ES, KISSYOH, CR-O79L+, CR-O86R+, 075LA, GOLGI, HISTON, PHAGE
--> for optionals: HISTON and PHAGE are not necessary unless your AC's really specializing in energy weapons. CODON and SS are more useful.
Tuning: Basically, a part's lowest stats gain the most per tuning point. Just play around with it and try to get as much per tuning point as you can. As long as your AC already has around 15000 cooling, you can devote most of your tuning to defense or weight reduction.
TYPE B:
Type B players have different techniques for shooting their lefthand guns.
1: use right index finger on the O-button. right thumb on X and square. right middle finger for R1 and R2. Will take time for index finger to get used to the awkward position.
2: remap the controls. Left arm on triangle, change weapon on O. Use tip of thumb to hit both square and triangle
3: default controls but use the tip of your thumb to hit square. Thumb-joint hits X. Middle/base part of thumb hits O. (LOL only Leperman is capable of this)
4: Type B but use left analog stick for movement. Place left-hand controls on L3.
5: Be normal and just tap circle occasionally.
EDIT: LOL beaten by Rick.
EDIT 2:
For some ideas for ACs using different leg types and weight classes, check out the garages by me and Leperman. Note FCS choices given the weapons, tuning, and Generator-Booster-Radiator combos.
http://ravenrepublic.net/forums/showthread.php?tid=1871
http://ravenrepublic.net/forums/showthread.php?tid=1887
Anyway for now, I'll let this thread stay in game help. But as we shift the discussion more towards just your AC design, I'll move this to LR designs.

For starters, you can take a peak at this (huge) thread for a previous new player:
http://ravenrepublic.net/forums/showthread.php?tid=1978
It's quite a read but it'll most likely answer many of your questions.
So onto your AC. I see that you like low-drain light-midweight bipeds. That's perfectly fine. And most AC players tend to prefer that AC class.
Anyway, onto appraising your parts again:
Head: YH12-MAYFLY --> (nothing particularly good about this head. The S2 you were using before was better. But like I said, pair it with the 69RA starter radar)
Core: C9BE2 --> So-so as an Exceed-Orbit core. But there aren't many alternatives. A standard hanger core like 98UL or U2 is usually better. But I guess it pairs nicely with your PIXIE3 here.
Arms: MACAQUE --> great arm. One of the best in its class.
Legs: DINGO2 --> heavy lightweight / light midweight. Low drain. It's no wonder you were drawn to this leg. Really good set, but don't let it restrict your growth. It has a tendency to do that.
Booster: VULTURE2 --> excellent. But it pairs better with the G91 generator UNLESS you're using an OB core.
FCS: MF03-VOLUTE2 --> decent FCS for standard-type weapons but doesn't really go well with your PIXIE3. F73H (SW) is probably your best bet, considering both your P3 and missiles. COWRY (WS) will give you the biggest lockbox but will limit the range of your missiles.
Generator: G01-LOTUS --> nothing really wrong with this. But G91 will give you more energy faster
Radiator: ANANDA
Inside: NONE
Extension: CR-E92RM3 --> best missile extensions in the game.
Weapons:
Nymphe is nice. But usually, it's paired with missile-specialized FCS like MONJU so that you can maximize the number of locks.
PIXIE3 is a great machine gun. But your previous R2 is probably more versatile and easier to use.
Optionals: O01-ANIMO, CR-O69ES, KISSYOH, CR-O79L+, CR-O86R+, 075LA, GOLGI, HISTON, PHAGE
--> for optionals: HISTON and PHAGE are not necessary unless your AC's really specializing in energy weapons. CODON and SS are more useful.
Tuning: Basically, a part's lowest stats gain the most per tuning point. Just play around with it and try to get as much per tuning point as you can. As long as your AC already has around 15000 cooling, you can devote most of your tuning to defense or weight reduction.
TYPE B:
Type B players have different techniques for shooting their lefthand guns.
1: use right index finger on the O-button. right thumb on X and square. right middle finger for R1 and R2. Will take time for index finger to get used to the awkward position.
2: remap the controls. Left arm on triangle, change weapon on O. Use tip of thumb to hit both square and triangle
3: default controls but use the tip of your thumb to hit square. Thumb-joint hits X. Middle/base part of thumb hits O. (LOL only Leperman is capable of this)
4: Type B but use left analog stick for movement. Place left-hand controls on L3.
5: Be normal and just tap circle occasionally.
EDIT: LOL beaten by Rick.
EDIT 2:
For some ideas for ACs using different leg types and weight classes, check out the garages by me and Leperman. Note FCS choices given the weapons, tuning, and Generator-Booster-Radiator combos.
http://ravenrepublic.net/forums/showthread.php?tid=1871
http://ravenrepublic.net/forums/showthread.php?tid=1887