I was training agility at Ape Atoll, and I was running low on food, I had 15 hp, and I decided that i was going fishing on the fishing spots nearby, when i took my monkey gregree, a scorpion appeared and hit me a 15, and i died. :wall: Hopefully I didn't lose anything valuable.
You should go to Wildy Agility Course for faster exp, and less failing, but if you are afraid of pkers, you should go to ape atoll course. At lvl 57 you will fail often so bring lots of food, but is good exp.
To get infinity clothes you need to do all of the games of the Mage Training Arena. But the best for exp I think the one where you use cosmic runes to enchant.
Well, it depends on your Combat lvl, the time you play a day and the assignments you get from slayer masters. But on average I think it takes 3 to 4 days. It's difficult to predict.
I think fire giants are excellent to train on with guthans, you can go to mellee room wich is normally not too crowded, use whip when your health is high, and when it gets lower than 60 use guthans spear to heal, and you can get some good drops from them.