Mods for a '99

[Homieazteca]

So,

First: On sound, I'm looking to up the sound a bit, when i got berchenko it came with a sony hu and some speakers, i changed them on the spot for a pioneer hu and 4" speakers with a set of tweeters next to them, i also place some sort of foam i had and now i can hear some bass, can't to over 42 on volume tho. But now, shere's no speakers on the door, id like to mount some 6,5 2 way 300w (cant remember the make, theres no hole, dont know if theres cables, i'll update).
I have a vector 6 channel to power some rear speakers* and one or two 8" depending on space.
*rear speakers.. Where? I cant find a place. Theres some places in the back next to the back door framepost that might fit a 3.5" but i think its too much work for no real gain. (Only my dogs in the trunk will hear)
I guess basic sound implies a 6x9 or so. Any ideas on the place?
The subs i was thinking on the trunk left side where the net is, custom fit some flat box, but how are the acoustics? Again, dogs.. (Cant leave them deaf). How about under driver seat, similar flat box. I have an active flat sub, sounds Ok, but ideally goes to my wifes audi to help.
All is equipment that has been in my last 3 cars.

Second: suspension: i'd like to lower a bit, here they sell to lower 25mm(if i understod right, still learning local toungue) for €120 (full set of springs, no shock), i like the ride, feels good but here, the countryside roads are curvy and wavy, i feel the roof pulling aaaggggrrr, it sticks good.
Anyways, id like somethint that wont affect so much the damping (as in how the shocks absorb hits) but gets me a bit more sporty(?) feeling, i don't really carry heavy loads nor id like to lowride it. Family man. Question is: whats the drop?

Wheels, i think mine has metal rims, 14", can i put 15"? I think i can. But only summer rubbers.

What else? Any body knows how to gain a little torque on a 1.8 petrol? I feel like mine could use a tune up.

How about the roof? I think there is enless possibilities, is there screw holes behind the cover? How about a big custom box with lots of ideas inside? Would it drop or hold? I've seen these special inside bars for skies. How much weight can those side holes take?(where the bars go in).

Lets hear it...