The year that the store was established is 1978.
The sign text needed to solve the puzzle is TOOLS FOR WOODWORKING.
Below are the changes to the sign text:

1)  TOOLSFORWOODWORKING

2)  TOOLSFORKING

3)  TLSFRING

4)  NOITLSFRING

5)  NOITLSRIF

6)  NOITATSERIF

7)  FIRESTATION (which again, can be found across the street)

The year that the Virginia-Highland Arboretum began is 2009.

The solution to the maze intersects with letters that spell FOLLOW LANIER AVENUE UPHILL TO NEXT INTERSECTION.

The name of the statue as seen on its plaque is BULWARKS. When those letters are connected with a straight line, they will intersect with words to reveal CONTINUE FOLLOWING CURVE OF LANIER TO HIGHLAND INTERSECTION.

At the intersection’s street signage, the top street name is LANIER, and the bottom street name is HIGHLAND. The code of letter coordinates can then be solved to read TAKE HIGHLAND AVENUE BACK TO STARTING POINT.

The number of housetops from Clue #1:  3.
The year that the store from Clue #2 was established:  1978.
The year that the arboretum began from Clue #4:  2009

When the letters assigned to those numbers are inputted into the code, the name of the Indian nation that ceded land that would later become Virginia-Highland is MUSCOGEE.