I am not experienced in hardscape but am taking the plunge at the request of a family member. I am replacing a deteriorating flagstone walkway that seems to have fell victim to a poor concrete base that doesn't appear to have been thick enough, mixed properly or reinforced adequately. The walkway has several turns and is approximately 40' in length. It is my plan to compact 4" of stone and then pour a 3" concrete base to serve as the base for my mortar and stone walk. The property is in zone 5. The questions I have are whether the depth of my planned 4" stone and 3" concrete are appropriate. I was planning to use rebar to reinforce the concrete but I wanted to know if this was appropriate and whether I need to also have expansion joints. If I do need the joints, is there anything that I need to do differently when the concrete is for a base rather than a regular walkway. Finally, should I seal the concrete prior to laying the stone and mortar how long should I wait before beginning my mortar and stone work? Anything else you might be able to add would also be appreciated! I'm pretty confident that I will get the job done right, but it never hurts to run my plans by the pros. If this little endeavor doesn't work out, I'll just stiff to my carpentry and remodeling work in the future! Thanks.