Since the only weed guard jig heads I can find are round is this ok or do I need the mushroom style?

It will work fine. I wasn't able to find any mushroom style with a weedguard either so I had to start making my own. 

I make a mushroom jig head and then I use a Slide-off weed guard.

 

http://www.slideoffweedguard.com/

I'd stick with the mushroom head. Check the Table Rock forum on ozark anglers,. there are several sources for them there.

I have been using these mushroom heads for tubes and always had a problem of getting them hung up, I'll check out those slide off weedguard and see how it goes.

are they new? I never heard of such a thing.