The distance between the top of the fret to the bottom of the Low e string is 4mm. Is that too high?
I've always used the playing card test for my action. If you can stick a playing card under the low e at the first fret, and it sticks in there on its own, the action is perfect. That's all assuming you can play open e without fret buzz.
can i lower it myself? i think mine is a little high. But if fret buzz occurs after i lower it myself then im screwed.
well not COMPLETELY screwed, but replacement bridge/saddle pieces aren't cheap. I'd leave it to a pro if I were you.
The saddle just sits in a groove. Not rocket science.

Partscaster/Tele into a bunch of pedals, a Maz 18 head, and a Z Best cab.
And you've seen the intelligence level of these boards. Not exactly a bunch of Nobel Prize winners.
Quote by roamingbard13
The saddle just sits in a groove. Not rocket science.

You got to set it up right or you have stuffed your intonation.

The action should be what feels best for you. I prefer it lower, but thats just me.
Adjusting the action at the saddle is always the last adjustment I do on an acoustic. You want to make sure your guitar is properly humidified before setting it up though. A very basic acoustic guitar set-up could involve (and in this order):
1. truss rod adjustment
2. nut adjustment
3. saddle adjustment

How to adjust the saddle:
Typically, I lower the saddle on acoustic guitars by removing the saddle from the saddle slot in the bridge and sand away the necessary amount of material from the bottom of the saddle. You want to be sure to leave the bottom of the saddle flat or your tone and string balance (especially if you're using an under the saddle pickup) will suffer.

Don't forget that any adjustments you do to the saddle will be mitigated by half when measured at the 12th fret. For example: lowering the action as measured at the 12th fret by 1mm will require you to remove 2mm at the saddle.

general measurements:
Lots of my clients like their action to measure 2/32" at the 12th on the 1st string and 3/32" at the 12th fret on the 6th string (measured from the top of the fret to the bottom of the string).

Here's how I adjust a saddle (skip to the last few pics):