Hey Solstice. I'm thinking I'm going to make 'grab' a separate button on the next release. I feel bad about having a re-release so early so it probably won't be until there's another large update.
As for combos. I was planning on creating some how-to vids for each of the characters when I had the time.
What I can tell you now is that the timing is fairly loose in most instances. You can sometimes press the next button before the first attack has finished.
In Syclant's case, say, you can just type j,k,l to get his light, med, strong combo in the time it takes to say '1,2,3'. If you want to get Tail Spin into Fury Attack. As soon as you press the execution for Tail Spin, you can press forward, down, forward, attack and by the time you finish it will have combo'd. If you see the opponent is blocking, just stop yourself short.
Likewise, with Fidgit, you can press close strong (the elbow), medium, then hold medium, and it'll automatically combo into Cometpunch.
It would probably take some practice, but generally, you can execute moves a little before you want them to happen in a combo and itll follow through.
edit: I started working on this game last February, but the going's been slow between learning how to use FighterMaker and the rest of my life. I suggest
http://www.fmhq.us/index.php as a starting point. They have a couple of useful tutorials and a semi-active message board. Most of what I learned I gleamed from looking at the sample game they have for download, and asking about the rest on the forum.