Wanting to build a garage (Need advice)

Both styles of roof you are asking about should meet code. Not sure about your area but probably BOCA.

As for cost - Probably comes out about the same; although with pre-built truss you can have the building started and finished in a few days. (Used to take us about 4 days with a crew of 4) Pole Construction. Building truss on site will take longer, I always hated building them on site.

As for height- I think your ceiling needs to be higher, 10' is cutting it too close. Average car about 4' truck maybe 6' and at times you may want to lift it 6' to fully walk under, lower to actually reach certain parts of vehicle. So I would go 12' at minium. My last garage I built was 12' side walls, I was going to do a lift but sold it before I put one in. My next one will be at least 14'.

I just got a quote for a 32x40 x 16 high; it was $9000 installed. It wasnt very much more to go higher; although I know you have height restrictions.