In reference to the verses in Eccl. I don't believe the Old Testament or New Testament Saints are referred to as "the dead."  These are those who died in their sins. Paul said to be absent from the body is to be present with the LORD. Those who are saved are "the living". When Christians die, only the body goes to the grave, but will one day be reunited with the spirit and soul at the Rapture.
 
As to the cloud of witnesses, I believe they are made up of Old Testament Saints, New Testament Saints, angels, and all who have died in Christ and gone to heaven. The Bible says there is rejoicing in heaven among the angels when one sinner gets saved. I believe the angels witness this. I also believe from time to time God rolls back the clouds and allows our loved ones in heaven to see what is going on here on earth, when it is good. I don't believe they see us all the time. They certainly do not "watch over" us as is taught in New Age and on television.
 
Herein lies your friend's fallacy. Just because we can be seen by those in heaven does not mean we can communicate with them. The Bible forbids communicating with those who have died. I do not believe it is wrong to talk to your loved one who has gone on. Just don't expect an answer back! Because the Bible says, "love never dies" I believe we always have a connection to the ones we love. Based on that, I believe God will allow my loved ones in heaven to see through the clouds and hear me when I want to tell them I miss them and love them. They have not forgotten us just because they are in heaven. And should I be wrong about that, what is the harm, if I am comforted and have not violated Scripture? God is so powerful He can work anything out for us.
 
My Dad never lived to see his great grandson, but I believe by God's grace he has looked down and seen him now.
 
To get back on track for your friend: Angels do not carry messages back and forth between people. Angels only convey messages from God and that at God's direction and not at our will. (See the book of Daniel). Also we CANNOT pray to the deceased. Only God answers prayer. I believe this is one of the reasons we are not to communicate with the dead. Humans have a tendency to pray to people and even angels, if they don't know what God teaches about that. I also believe any spiritual knowledge outside the Bible or not coming through God is very dangerous. The devil is a deceiver and will use our own natures against us.
 
Your friend raises some valid questions. We have all probably had some of the same questions. Good for her. We will not get to the truth, if we don't seek the truth. There is wisdom in numbers and I look forward to what other Doves have to say on these Verses. May the Holy Spirit teach us all and enrich us thereby.
 
Blessings,
Shelva