Water until established and then cut the water back.  Bermuda needs water, but not as much as some of the other types of grass.  Keep it cut short

sounds like too much water.  Pine straw has acidity in it and helps transfer the nutrients properly to acid loving plants.  Fertilizer could also be needed.  Plant nutrient deficiencies vary and sometimes the necrosis in the leaves can identify the issue or which nutrient is lacking... 

Gardenias, I love Gardenias!  Have you tried a fertilizer for acid loving bushes?  You can go to a nursery or even The Home Depot or Lowe's and explain what's going on, and then they can recommend what you should do for them. 

Besides the painting suggested by Chad of Lonestar Painting which can truly makeover the appearance of a home, I suggest that the trees and shrubs be professionally trimmed and thinned out.  Application of weed control and fertilization of the lawn will provide a healthy and attractive canvas to your yard that can be supplemented with a dose of spring color annuals

A very quick and cost effective way to upgrade your homes exterior is a cleaning and color change. Pressure wash to clean it up and paint the shutters and front door.  They can remain the same color or pick a fresh new color.  You can also take any old fixtures that have faded over time and paint the metal with a fresh satin or gloss paint.  Same with metal railings or metal awnings. Possibly a one day job with big results. 

We just had sod installed at the office here at Crown Builders in Charlotte, NC.  The landscaper told me to water each day for 15 minutes the first 10 days.  From 10-21 days after install water every other day.  After 3 weeks and beyond cut the lawn as needed.  It should be fairly well rooted and can take normal wear and tear. Give it 1" of water each week.  Apply balanced turf fertilizer 6 weeks after install.

Depending on the severity of the runoff you might want to contact a Civil Engineer. As an engineer myself, with a specialty in drainage and hydrologythere are many issue to consider when dealing with offsite drainage. For instance if you redirect it on to another property it's possible you could be held liable for any impacts tha occur. Just a thought.

We agree with Geoff's suggestion and would also recommend speaking with a local landscape architect. They not only handle plant specifications, but also deal with drainage and irrigation. They will be able to assist you or point you in the right direction to solve your issue.  

A landcaping contractor might help. Depending on your location, you may be able to find someone here: http://www.guildquality.com/find/Landscaping-and-hardscaping/North-America

You can install a flexible downspout extension on your downspout that is next to your front step and run it behind your bush out past your mulch to keep the water from washing your mulch away.  You can buy the flexible downspout extensions at Lowes or Home Depot.