2007 Toyota Camry leaking oil?

Usually I change the oil every 3,000 miles; the manual says I can do it every 5000 miles so in some point I did that but mostly I do it every 3000 miles. I use the 0-20 or 5-20 which the manual says is what I should use. I'm not sure how many miles it takes to burn one quarter but let me tell you that the oil was changed recently and the stick showed it was to the second dot which I believe it shows it is full (that what the mechanic told me). He said when it gets to the other dot it will mean you need a quarter. I just checked it and it shows the oil is between the two dots and I have driven it 587 miles. I hope this gives you a better idea.
About the PVC, I have no idea, can I check that myself or should I take my car to the mechanic to check it?

Thanks

Ok. Should I write you back after I see that it needs a quarter of oil? Do I need to remove the cover of the engine to replace the valve? I dont remember when and if I has been replaced.

I have been using synthetic oil. But about 4 times in the last two years I use conventional oil.

Should I use synthetic or regular? If I use regular, which one should I use 0-20, 5-20 or something else? Does it matter?

With the Synthetic oil it took 1000 miles to use one quarter. How do I know if the PCV is bad? I read that there is a test that needs to be done to check the PCV because it could also be the hose that might be clogged? Also, what would happen if the valve is bad?

Thanks