Whether you do either project yourself or hand them off to a pro depends on how much patience & determination you have, how much you are willing to spend & what finish you would like to have on each... if you want them to look as if they are fresh from the factory, take them to a pro . if you want them to look damn near factory finished and have a faair amount of time on your hands I say go for it. 

The chair itself may look difficult but in fact is fairly easy if you just take it one step at a time - have a lot of patience, do a practice run, cutting guide/test pieces from muslin or an old sheet and use the original pieces as guides... Be sure to have a good staple gun, an upholsterer's sewing needle and a fair number of band aids at the ready & you will be good to go ...  and if you make a hash of it THEN you can take it to the pro to get them to fight it out!

As for the buffet, with the right wood filler, sand paper, an assortment of stains, a mixing bowl  & a bright light you could probably handle that one as well...

thats my 2 cents - take it for what its worth. 

I wish we had an interactive webcam because I could walk you through the reupholstery if you wanted to learn it.  A few techniques and some practice are all you need.  The chair isn't too complicated but obviously more work than a kitchen chair.  If I had one just like it, I could show you step by step.

You can do what you want with the chair legs, but the upholstery is really for pros. The upside is you can choose exactly what you want the upholstery to be. I'm thinking zebra or leopard -- faux of course. Legs could then be stained or finished to complement that. 

As to the buffet, you are sort of hosed unless you can resolve the deep scratches. Problem with that style is that the slightest mar anywhere sort of ruins the whole thing. If you can resolve it to invisibility, you're better off refinishing or painting.