I don't know about the harvester (depending on exactly what you want to do) but the stuff with the energy cell is definitely possible.
Getting the information is moderately easy especially if you know how tables work. Depending on how fancy you want the monitor display to be, and how many different things you want to display, making a monitor display goes from easy to hard. If all you want to do is display energy storage as a percentage or something like that then it is easy.
I don't have time to go into it in too much detail but tables and iterating through tables seems to be where most people stumble when they are new to computer craft (I am thinking of starting a thread to help generally with this sort of thing).
Tables are like supervariables which contain any number of subvariables. A table is a normal variable of type "table" (all variables have types, i.e the name of a class of variable - in Lua these include "number", "string", "boolean", "function", and "table"). The values stored within a table can be of different types. Each value in a table is referred to by a key. By default, numeric keys are assigned starting at 1. You don't have to use these keys though and you can assign any number or any string to be the key for a particular value.
In lua there is a loop called the generic for loop which can do many different things based on an iterator function - in this case the iteration function I will mention is called, in pairs. in pairs allows you to cycle through key,value pairs in a table.
peripheral.getMethods returns a table which you can store in a variable of any name you wish. You can't just print this table though (I think when you get table:4wfewf4 it is referring to its point in memory). To print out the stuff in side it you need the generic for loop and it goes roughly like this
Code:
local myTable = methodThatReturnsTable() -- replace this whatever you are doing
for k,v in pairs(myTable) do
--For each point in the table k stores the name of the key and v stores the value. You can always print k out and so long as v is not of type "table" or --type "function" you can print that out too
print(k)
print(v)
end
When you get the hang of it, I promise you it is not too bad.
I am not entirely sure what your problem with the peripheral wrapping is but I have an idea. It sounds like you don't have much experience with wrapping peripherals so I will tell you about that too.
When you wrap a peripheral you end up with a handle to that variable which you can store as a variable and you can use that variable to tell the peripheral to do stuff.
Like this
local monitor = peripheral.wrap("left") -- assuming the monitor is on the left hand side
The variable monitor is the handle on the monitor now. To test this, go into a creative world and spawn in a computer and a monitor and then look through the term api on the CC wiki -
http://computercraft.info/wiki/Term_(API)
For pretty much every method in that api you can remove the word term and replace it with the handle you assigned to your monitor peripheral.
Code:
local monitor = peripheral.wrap("left")
term.write("Hello World") -- prints Hello World to the computer console
monitor.write("Hello World") -- prints Hello World to the monitor
The same principle applies to every peripheral, including redstone energy cells (at least in 1.6.4 - sensors from openccsensors worked a bit differently before but that has changed now and it is the only exception that I am aware of). You do not need to wrap a peripheral to do the getMethods command but you do need to wrap it if you want to do anything else with it. When wrapping make sure to provide the side the peripheral is on, or if you are connecting via wired modem, use the string that appears in game chat when you click the modem to turn it red.
This is pretty much all the information I will offer in this thread because I am starting to repeat myself in several threads. It is only because I am so enthusiastic about this mod and I am happy to help where I can. I think I am going to start a thread of my own in the next few days which might clear this sort of thing up for more people.