"Just wondering do all oak trees give off acorns every year or is it every second year"

No. Google quercus mast years for lots of details. You could also search for oak mast, here in this forum for multiple mentions.

"how old does it have to be before you get the acorns"

Depends on the species, growing conditions, and other factors. I have seedling oaks of more than one species that have produced a few acorns at around 4 or 5 years old. Some oaks may take 20 years or more.

It depends on the oak. Some are annual and some take two seasons to mature. Some of the southwestern oaks can flower and produce acorns at a fairly young age(5 or 6 years).

I agree with all the above posts, but your individual tree may be different, there are hybrids that bear early. The Compton's oak is supposed to bear by year eight. It is a hybrid of Quercus VirginianaX Quercus Lyrata, Live oak and Overcup oak. My Chestnut oaks seem to bear well every year. These are exceptions to the rule, though.