soft ticking is common and shouldn't cause you any worry. if it's harsh, loud, and rattling, though, then that's your timing chain and you should get thee to a mechanic.
the misses you're talking about sound like what i had on my 560SEL a year or so ago. turned out it was a bad spark plug wire.
the smoke out the back is fine, provided it looks like water vapor and doesn't smell like burned motor oil...
lastly, i agree with the above posters -- take your baby for a spin on the highway. don't worry about breaking down -- the worst that can happen is you'll coast to the side of the road and call for a tow truck. not the end of the world. and if your car really is in so bad shape that it can't handle the highway, you might as well find out now, before you pour a lot of (unnecessary?) money into it for cosmetics and stuff. but i predict all will be just fine [

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