Ok, now i've eaten, i'll get to he rest of the post.
I have a gravel and a sand tank - sand since yesterday! I LOVE the sand, looks gorgeous and a lot of people says its better for planting. some will obviously disagree, i havent formed an opinion yet! Its also cleaner as the detritus cant fall through the gravel due to its compact nature BUT because of this, you rely on plants/ornamnets and filter media much more for the de-nitrifying process.
HAVE you read up on cycling a tank? you REALLY need to.
Though with live plants, this process is cut Much shorter/immediate depending on the livestock you add.
read this for a start;
now you said you want colourful fish that will eat other fish. you cant really have both. Most people go down the route of a community tank becasue they are great to scape and you can add some gorgeous fish in. predators, not so much IMO.
The 10 gallon that you spoke of, you could do the dwarf puffer tank i mentioned earlier for a ''predatory'' tank - though not quite in the terms you mentioned, but still.... and could have 1/2 in there........THOUGH i'd wait to do this until you are a bit more knowledgeable about the whiol fish keeping malarkey as they are quite demanding fish.
Until then you could use it as a quarantine tank for your bigger community tank IF you went this way.
What i'd really suggest more than anything though- IS SLOW DOWN. Start reading about the whole deal and asking questions, l'll gladly answer what i can all day for you, and so will others. The best key here is knowledge. Start looking up other people 29 gallon tank, and getting ideas, and then forming your own from them.
Keeping fish isnt just a buy and throw in, theres much more too it, and with a 29 gallon one of the things you'll encounter is fish need big spaces. You cant throw a small fish that will grow to 40 inches into a tank just because its only 3 inches now, it causes long term problems and mis-growth, etc etc, all things you'll hopefully read about.
yeah, im blabbering, and still hungry, so read a lil and ask some more Q's if you have them
And welcome to TFK