In my experience Malawian cichlids have been less hassle to keep than
discus, so long as you have the right combination of fish in the right
numbers in the right tank. That's where the challenge lies do some googling
to find the species that you want most and work from there.
Try http://www.malawimayhem.com/ they have a nice species profile section.

1: I medium sized Pebble substrate in the aquarium, will this suffice?
It's OK as long as you are using some other method of hardening the water
(ie/ a bag of crushed marble in the filter system) It's common for people to
use calcium carb or coral sand or something like it to help keep the water
hard. Of course if your tapwater comes out at the right level of hardness
already and you make regular water changes then you mightn't need anything
to alter the water properties.

2: I have 5 medium sized pieces of bog wood in the aquarium, is this OK?
They will soften the water, as long as your tap water is naturally hard or
you have some means of keeping the water hard then wood is fine, I like to
have at least a little for the pleco that invariably ends up sharing the
tank. I've heard algae eating cichlids might use it in a similar manner as
well.
3: I have 8 - 10 small - medium rocks in the aquarium. I plan to add
more. Will rocks help "harden" the water?
Some will, some won't. Here's a nice guide written by an Australian
geologist/aquarist http://www.gcas.org.au/articles/merjo1.html

4: What is the ideal temperature?
5: What is the ideal PH value?
http://www.cichlid-forum.com/article...lawi_setup.php

6: Should I add a fast water moving second powerhead to the aquarium?
Perhaps a Fluval 4 internal?
You want to filter the tank volume 6-10 times an hour.

7: I am currently cycling the tank with 4 mollies. I used the same
mollies to cycle my last 100 litre tank, this bunch are extremely hardy.
good idea, the mollies will be as happy as can be in water tailored for
Africans.

8: What is the best selection of cichlids to start with?
You can get some suggestions for species combinations/tank sizes here
http://www.cichlid-forum.com/article...rence_list.php
and here http://www.cichlidrecipe.com/cichlidrecipe/crp22.htm

9: How many cichlids will I put in to start with?
See above.

10: When should I put in the first batch?
I would suggest buying them young and putting them all in together at once
to save you the hassles of introducing new fish later on. That way hopefully
they'll establish a pecking order before the 'pecks' as lethal.