Bringing on some curb appeal....before

We added the large oak last fall.  Which is a great time to buy trees may I add.  For two large trees, we got the non-delivered price of $250.  They are both over 10 feet tall.  We picked out a River Birch for the back, to add privacy.  Then a Sawtoothed Oak for the front.  We're keeping the nice large Dogwood to the left of the front yard.  We've been talking about what we want to do here.  Maybe a rock wall around the oak tree.  I'd like to replace the concrete steps with large stones.  Luckily I have friends and an SO that worked professionally in building hardscapes, so I'll get their expertise and share it here. 

See this steep front hill?  I cannot mow it myself.  Which creates a problem.  Plus, it's pretty darn ugly.  We're thinking of covering both hill sides with a ground cover.  What do you think?