Greetings,
Let's look at a couple of things you mentioned. This is only meant as simple answers and can dig in deeper when I have more time later today!
There is power in numbers.
Meaning joining of faith
Look at it this way....if you are praying according to His Word (what He has already said) and praying by Faith then
You = 1 and Jesus =1 and the last time I heard 1+1=2. So then two of you are agreeing together.
Empty Prayer
No Faith.....No Expectations. ...No Hope.
Praying things other then what He has spoken in His word....such as trying to use Prayer to make some one do something.
Scipture says without Faith we can not please God. We are to walk by Faith and Not sight or feelings.
If you begin to judge your prayer time on feelings.....Our enemy the devil will give you all the feelings you could imagine.
What does His word say about prayers?
That's what you must believe.
Example, as you said, sometimes I feel like I am talking to a wall.
Question.....does this change how you are praying?
Have you ever said why won't you listen or change to a more begging type prayer?
There is No Faith in that kind of Prayers and are empty as last year's bird nest.
About the rest, for now will have to be in a pm, for the topic of tongues is prohibited in the open forum at this time.
See Here
Blessings my Sister
I can bring lots of scriptures covering all this a little later today, but for now I have got to go.
FCJ