I'm 2 achievements away from finishing the hard Varrock achievement diaries. I need 153 kudos, and I need 70 farming... unfortunately, my farming is 43 right now, close to 44. What's the fastest way to level, regardless of cost? I've got quite a bit of money I'm willing to put into it, 5-10m I'd say, though I would (of course) rather stay cheaper.

 

Second question, what's the fastest way to get kudos?

Kudos need quests done

For farming, grow the highest lvl tree, fruit tree, allotment, and herbs that you can. You could get 70 farming in a week

there is only 1 way to get kudos:

Complete the stuff inside the museum.

Start off with willow trees and curry trees at your level and move on as you can, willow and maple seeds sell for next to nothing. If money no object and you're in a rush just pay to protect all your trees/fruit trees regardless of cost effectiveness.

 

Once you can start growing watermelons do that. You might as well grow toadflax in your herb spots as well: small xp gain and some gp. Supercompost everything except the trees and fruit trees if you're paying the farmer. Plenty of quests give farm xp as well, looking at start of the Fairy Tale Series, Garden of Tranquility, Drunken Dwarf, Rum Deal, My Arm's Adventure and possible Back to My Roots at your level.

Watermelons, herbs/flowers + magic secateur yield ~10k ish exp per run (which is decent imo)

Farming the highest fruit trees/trees you can also adds a bit to exp.

 

Questing is probably one of the best ways to get farming exp as well.

http://runescape.wikia.com/wiki/Quest_experience_rewards

^This is a pretty good list.

 

Other then that, minesweeper/livid farm (requires level 60 farming) are your only real options.

 

The problem with farming is that - it's generally a "slow" skill that reward those who farm everyday.

There isn't any amazing way to grind out farming due to all the wait time involved.