OOoops I didn't answer all your questions....
Is there anyone who runs on this thread? Yep, me

and many others, I'm 52

and proud of it and I've been running for years....
Will I be able to run as far as five miles a day easily or will it always seem difficult now that I am older? Yes yo ucan run five miles after starting gradually, it'll take a couple of months but you can do it

NO it will not seem as difficult as the younger counter parts, because you will be in better shape after running that your younger counter parts. The young folks who have been running for ages will be better conditionned but at 42 you can get in extremely good shape in no time...
Let me know of other issues you have encountered that a younger lady may not.The only other issue for me was my knees, but with weight training and strengthening of my legs, and Glucosamine, I can say that I rarely have sore knees anymore...
My biggest suggestion would be to get a good pair of running shoes at a reputable running store where they analyse your gait and check to see if you pronate or over pronate...
Hope this helps, keep us postd on your progress...