Some options include magic combat (which is now much cheaper than it used to be), doing high alchemy, and training in the Mage Training Arena.
It looks colorful. It also gives some magic boost.
You need a magic level of 31 to cast telegrab.
You could drink Chefs Delight to boost your cooking level.
There is something called a "Protect from Magic" Prayer. But you need a prayer level of 37.
Can Not Be Done.
Yes it can, provided it stays higher than your Ranged Level.
afraid to say theres no such thing as ice burst on runescape
No, you can't, but you can boost your hunter level with hunter potions or evil Dave stews in order to boost your level high enough to loot the jars.
By using the highest level spell you can. Higher level spells give more experience.
It depends on how high your prayer level is.
Yes. Magic contributes to your combat level. Assuming you trained only Magic to 99, but left your HP at 10 (which is possible), you would have a combat level of 50.
The so-called "boosts" don't give you actual experience; they temporarily increase (boost) your level in the selected skill. In that case, yes, there are items that temporarily boost your LEVEL.