My macbookair tried to drink my coffee and now, everything is upside-down A few days ago, some coffee went on my MBA(4,2).

I immediately took it down, unplugged it from the magsafe, and started to open it to dry it the faster I was able to.

After a few days in rice and putting the piece back together I booted it. It was working quite well given what happened but now the fan are going full speed, even after SMC &amp; NVRAM reset. The SMC Fan Controller can see the speed of the fan (6500rpm) and I can't change it. Which is annoying.

But what is way more annoying is that now my trackpad &amp; keyboard are dead. Well, almost dead. Because I can still boot my mac. By the way, the keyboard backlight is still working as usual, enabled when a key is pressed (just the power key) and disabled after 10 secs)

How can I fix theses two issues (preferably with a lot of time and the less money as possible)? 

(ps: I didn't find better tags, please, feel free to fix this :) )
For the fan, you need to differentiate between a fan problem or temperature problem. You need to see if the laptop is over heating when running the fan at full speed. Use something like TG Pro.

For trackpad and keyboard, you need to be able to see input live, so that you can tell if the trackpad/keyboard is in fact dead or working randomly. BetterTouchTool gives a live view of the trackpad. Karabiner does the similar thing for keyboard.