Fox engines do leak fuel from the front end, that is normal. That is how they lubricate the front bearing and help keep it from overheating. Actually all engines used to do this too. But over time several engine companies put in shielded or sealed front bearings to cater to people who wanted more clean running engines. Unfortunately the sealed bearings leads into more bearing failures though. Now then Fox did try and test a number of sealed bearings but none of the bearings really held up well or had a long life, so they never adopted them.

Now if you have the older bushed crankshaft engine without ball bearings, they will ooze quite a bit of oil out of the front of the engine. That is normal for bushed bearing engines. K&B did put in some spiral grooves on their Sportster series of engines to stop much of the oil fron going out the front of the engine, but it tends to cause a lot of wear on the bushing right there at the front though.

Now with a new engine it isn't running as smooth as it could as you are running it more rich at first so it runs more roughly then. So yes it will vibrate more. The engine should smooth out considerably after an hour of running it in. Fox engines usually don't start running good until after about a hour or so or run time has been done. Now then some engines may need a longer breakein time period than other engines.Some Fox engines may be a little too tightly fitted together, these can be more difficult as it takes a longer time to break them in.

My old Enya 1.20R engine almost destroyed my engine test stand as it vibrated and ran so roughly on me. But it did the same thing when new and I first ran it then too. But it smoothed out a lot as I eventually leaned it out more and got it running more smoothly as it broke in.