1. Is Astral Projection wrong and sinful?
Why would it be wrong? Dangerous, perhaps. Not that there's a great risk but the Process to do so can become a great strain on your Mind.
And It's not a Sin since nothing execpt other People's idea of Right or Wrong can define it as such. If God has anything to say about it, he sure is keeping his mouth shut on the subject. If you shouldn't be doing it, you'll know.
1. Is Astral Projection occultic and witchcraft?
Absolutely not. There are those who practise both but they are not one in the same. Some Occultis and Witches and Wiccans are Vegitarians but that doesn't make Vegitarism Occultic.
Most people against it relate it to Summoning Demons or otherwise Communing with Spirits but in reality, these are two totally different fields.
3. Is Astral Projection even real and can it even happen?
Certainly. But you needn't take another's opinion on the subject. Discover for yourself, if you truely want to experince it.
4. If it is possible how would you do it?
That is a complecated question and would require more time and effort then I'm capable of giving here.
5. If it is real and possible, then would a person be opening himself or herself to Demonic activity?
No. Like I said, these are two different things. They're aren't Completely unrelated as there is a link. But the Key to remember about Demons: They have no power other you except what you give them.
But, you must first ask yourself whether you are capable of taking such a Step. After all, Experinces like these aren't for a Faint of Heart or Weak-Willed. You will experince a side of the Universe that you could never Fathom even in your wildest Imagination and worst yet, you'll discover a side to yourself that will scare the Crap out of you if you aren't willing to accept what you find.
Like I said, it's not exactly "Dangerous" but rather more Spiritually Taxing and a little Mentally Crushing. Your Worst Nightmare would do little to prepare you for what is out there.