I recommend high alching items like maple longbows (u) or yew longbows because when you alch them they gives you more coins than if you sold them.
No, you still do lose a bit.
No, any item gives the same exp.
yew longbows
High Alch Yew Long Bows.
You cannot alch a Dungeoneering item.
To be honest with you, you shouldn't really lo-alch anything since it would be a waste of runes or/and cash spent on those runes, unless you make platebodies steel+ yourself, then low alch them.
Adamant Platebody
It all depends on what your level in magic is, and if you are casting the high alch or low alch spell. If I were you I'd use a runescape calculator. Here are 2 calculators below I like to use. I hope you find this useful
You go to your spellbook and select "enable defensive casting" on the bottom. Then, do magic in combat, not High Alch or Teles or anything.
go to the highest floor in the wizardtower and there is a lesser demon, you can kill... (good place 4 ranging 2 I guess) If you are 21 you can begin with money making for low alch (you'll get alot of loss) low alch till you are 55 and then you just high alch till 99 (you'll gain a bit loss)
If I were you just alch feathers until you get high alch, then you can start alching to make profit. -------------------------------------------------------------------------------------------------- Or you can alch steel platebodies.
I think you can alch it and get profit.