I ended up going with the trial version of FontCreator 8.0. If everything goes along fine, I'll buy it.
But the learning curve has officially started :P I'm having trouble understanding how the OpenType script coding works. And couldn't find any decent guides online.

The "import image" and "composite glyph member" works perfectly though, and was very easy to understand.

Code:

script latn {
feature Ligatures;
}

feature Ligatures liga {
sub b a -> ba;
sub b e -> be;
sub b i -> bi;
sub b o -> bo;
sub b u -> bu;
sub b y -> by;
}

I'm getting:
Compiling script...
[Error] (21,3): Syntax error: "lookup" expected but keyword "sub" found
Failed

I see. Thanks for the quick response.
Since I presume I'm not going to be using font creators for much other than this particular project, I want to avoid costly software if it's possible. Can you recommend any free (or cheap) software that'll suit my needs?

(preferably with a well working "import image" feature, since I've already made most of my glyphs as .png files)

First of all: I have literally no experience with creating fonts, so explanations should be made in dummy format :P
Also, therefore, this is probably not the best project to start out with, but I trust my patience and determination to get me through it.

What I want to do:
- Create a font that uses syllabary glyphs, creating 1 single glyph symbol when 1 latin consonant + 1 latin vowel appears together.
- http://en.wikipedia.org/wiki/Hangul is a good example: when typing the letters [H]+[A]+[N] in sequence, one single symbol: 한 (HAN) is automatically created.

(There are also separate symbols (base symbols) for all consonants and vowels. When combined, the vowels are used more or less like diacritics.)

Is this possible, and how? (P.S.: I don't want to use autocorrect functions)


STEP 2:
Also, I want these symbols to be placed quite closely together. In normal fonts, each letter uses a squared space of it's own. E.g.: when typing "VA" the lower part of the A doesn't start before the upper part of the V ends. I want my glyhs to have the ability to utilize that blank threesome space.
E.g. VV would appear just like that.
While VA would appear with a small overlap.