Yes, providing he does not sense your intentions and square himself away...that is when you will put him in your guard. I don't recommend the guard as a primary fighting position, but it is better to have him there than on your back.
As for your second question, I felt very comfortable with my stand-up fighting capabilities before getting into submission grappling. I started ground-fighting after about 10 years of training under Bob bethoney, I was a two time Uechi sparring champ, and a close combat instructor for the U.S. Marines.
I got into ju-jitsu (Brazilian) when a friend of mine and myself were training one day. He had been training with renzo Gracie, he was also a 3rd degree in Uechi. I found that not only was his stand up fighting as good or better than mine, but he could, and did, take me to the ground anytime he wanted to...no matter what I did to try and stop him. When he got me to the ground, he was a shark, and I was the person who could not swim. I'm not exagerating.
It was at that point that I knew I had to try my best to master this art and pass it on to my students.
When I started to learn Brazilian, sometimes I felt as if I was betraying my sensei or my system. I can still imagine my sensei saying things like, "Stay with Uechi...you don't want to be a jack of all trades but a master on none." I don't know how he feels about cross training these days.
I still love Uechi, but I also know you MUST know how to take an opponent down in many different ways, then know what to do from there.
Sorry for the wordiness.
[This message has been edited by Joe Sullivan (edited March 27, 2001).]