1998 200sx noise problem

I have a 1998 200sx se that I got a few months ago.
I was noticing some steering wheel vibration and when I went to brake and slow down, there is what sounds and feels like a loud tire sound for the last 10-20 mph.
I went to have the tires spin balanced soon after I got it. The guy
tells me my tires are wearing uneven,cross thread I think.
So I got some new tires instead and went and got my front end alignment.
I also needed front pads, so I got some Wagners thermo quiet pads.
I now have no vibration from steering wheel and no pulsating from brakes.

Well I still have the a loud tire sound when slowing down?
Someone told me maybe it's the brake pads, he says the car should have
porcelin type pads. Would this be the loud slowing down sound?
The tires I had on the front are on the back and the new Dayton tires are on the front. I didn't have the money to buy some expensive tires, but my Dad has Dayton tires are his cars and has no problem.
I know this sound is not normal, but I need help in figuring this out?
Can anyone offer some help or advice?

One other weird sound. Also when I'm brake and am about to stop all the way, I hear a bump sound coming from the back or trunk area, like something loose in the trunk. But I have removed everything that is in the trunk and the sound is still there. Any ideas.

Thanks, Danny

Anyone have any ideas?

Thanks again.

i put slotted rotors on my moms 98 gxe and it makes some funny noises at the end of braking, if the pads are super hard its not uncommon to hear a funny sounding noise but as long as you arent gauging your rotors theres nothing i can think of that would be a major problem, as for your trunk noise, could be a loose or missing bushing, broken strut mount, blown shocks, who knows