Aveo sedan 3 questions

I have an Aveo sedan 2007 and I have a couple of questions about it.

1. If I lowered it, would it be rickety? I was going to lower it but someone told me if I did, it would drive bad and be all rickety. Is this true? Like if I only lowered it around 6-8 inches?

2. Can I install a head unit into it? I heard that most head units only work on music dashboards that are 4 inches or under. Im pretty sure mine is 4 inches, but if it's bigger, would I still be able to do it?

3. I heard that if you get bigger tires than what the Aveo already has, it will mess up your speedometer, and you could be going more than what the speedometer says. Is this true? Because I want to get some bigger tires and rims. But would it really do that?

I'd really appreciate the help. Thanks. :)

Edit: Sorry, I have a 4th question.

4. Don't ask why. It's a stupid reason, but how much would it cost to downgrade from electric windows to roll windows, and where could I get it done?

do i answer this or do i not?

hell-here goes:

you cant lower an aveo 6-8 inches or you will be draggin ass. 1-1/12 inch drop is about as far as you will want to go. look for H&R springs online for the aveo. they are about 200$ and will give a nice ride.

you can install an aftermarket headunit but since you are asking this question i would suggest you go to a customs shop and have them do it.

as for rims and tires. the biggest you can go safely is 18s. id reccommend 17s and under with some 205/30/r17 tires. your best bet would be some 15s or 16s tho. and with the 17s and the smaller sidewall your tires will not actually be alot bigger than the overall size of the stocks so ur speedo changes will be minimal. besides as far as i know the speedos are off in the aveos by 7% anyways.

im not even gonna bother with the last question.