cut willows until level 70 woodcutting then cut yews until 99.
Nope.
Don't use macros jagex can detect all macros and you will be permanently band
I suggest you use a RuneScape skill calculator to figure out this kind of things. There is a good one at runescape.salmoneus.net.
The total exp is 13,034,431 experience for a 99 stat on RuneScape.
There is a girl that has 99 on all skills her runescape name is 'xxphatmagexx'.
TRAIN
you train it
There are no cheats in RUneScape. Getting level 99 in ANYTHING requires a considerable effort.
you keep training your skill to get up to lvl 99
Fish Salmon & Trout in shilo village to 99.
By fighting.
level 138. there is no higher level on runescape (for players)