The 1st is E. submammillaris f. variegata, I believe. E. ferox seems correct for the third. Sorry, I can't help on the others. You might want to check this excellent Euphorbia site for your others: http://www.euphorbia.de/indexe.htm
Thanks for the link Rosemarie, I believe you are correct about the first one, I also think that # 2 is possibly an E. Meloformis and #4 might be E. Fimbriata...still searching.